Compressible non-fibrous adjuncts

ABSTRACT

Stapling assemblies for use with a surgical stapler are provided. In one exemplary embodiment, the stapling assembly includes a cartridge having a plurality of staples disposed therein and a non-fibrous adjunct formed of at least one fused bioabsorbable polymer and configured to be releasably retained on the cartridge. Adjunct systems for use with a surgical stapler are also provided. Surgical end effectors using the stapling assemblies are also provided. Methods for manufacturing stapling assemblies and using the same are also provided.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to U.S. Provisional Patent ApplicationNo. 62/900,708, filed Sep. 16, 2019, and entitled “Bioabsorbable Resinfor Additive Manufacturing,” U.S. Provisional Patent Application No.62/913,227, filed Oct. 10, 2019, and entitled “Bioabsorbable Resin forAdditive Manufacturing,” and U.S. Provisional Patent Application No.63/053,863, filed on Jul. 20, 2020, and entitled “Compressible 3DPrinted Scaffolds,” the disclosures of which are incorporated herein byreference in their entireties.

FIELD

Compressible non-fibrous adjuncts and methods of manufacturing and usingthe same are provided.

BACKGROUND

Surgical staplers are used in surgical procedures to close openings intissue, blood vessels, ducts, shunts, or other objects or body partsinvolved in the particular procedure. The openings can be naturallyoccurring, such as passageways in blood vessels or an internal organlike the stomach, or they can be formed by the surgeon during a surgicalprocedure, such as by puncturing tissue or blood vessels to form abypass or an anastomosis, or by cutting tissue during a staplingprocedure.

Some surgical staplers require a surgeon to select the appropriatestaples having the appropriate staple height for the tissue beingstapled. For example, a surgeon could select tall staples for use withthick tissue and short staples for use with thin tissue. In someinstances, however, the tissue being stapled does not have a consistentthickness and, thus the staples cannot achieve the desired firedconfiguration at each staple site. As a result, a desirable seal at ornear all of the stapled sites cannot be formed, thereby allowing blood,air, gastrointestinal fluids, and other fluids to seep through theunsealed sites.

Further, staples, as recessed channel as other objects and materialsthat can be implanted in conjunction with procedures like stapling,generally lack some characteristics of the tissue in which they areimplanted. For example, staples and other objects and materials can lackthe natural flexibility of the tissue in which they are implanted, andtherefore are unable to withstand the varying intra-tissue pressures atthe implantation site. This can lead to undesirable tissue tearing, andconsequently leakage, at or near the staple site.

Accordingly, there remains a need for improved instruments and methodsthat address current issues with surgical staplers.

SUMMARY

Stapling assemblies for use with a surgical stapler are provided. In oneexemplary embodiment, a stapling assembly includes a cartridge extendingfrom a first lateral end to a second lateral end with a longitudinalaxis extending therebetween, the cartridge having a plurality of staplesdisposed therein, the plurality of staples are arranged intolongitudinal rows that extend between the first and second lateral ends,each longitudinal row having a frequency of staples in which the staplesare arranged along the longitudinal axis and configured to be deployedinto tissue, and a non-fibrous adjunct formed of at least one fusedbioabsorbable polymer and configured to be releasably retained on thecartridge such that the adjunct can be attached to tissue by the staplesin the cartridge, the adjunct comprises a lattice structure having aplurality of repeating unit cells, each unit cell having a non-uniformthickness, the plurality of repeating unit cells being arranged intolongitudinal rows in which each longitudinal row has a frequency of unitcells. The frequency of unit cells is different than the frequency ofstaples and the staples legs of the plurality of staples are configuredto advance through different portions of the adjunct with each portionhaving a relative thickness difference.

The staples can have a variety of configurations. For example, in someembodiments, the frequency of staples can be greater than the frequencyof unit cells in each corresponding longitudinal row. In otherembodiments, each staple of the plurality of staples can include a firststaple leg configured to advance through a first portion of the adjunctwith a first thickness and a second staple leg can be configured toadvance through a second portion of the adjunct with a second thicknessthat is greater than the first thickness. In some embodiments, eachstaple of the plurality of staples can include a first staple legconfigured to advance through a first portion of the adjunct with afirst thickness and a second staple leg can be configured to advancethrough a second portion of the adjunct with a second thickness that isless than the first thickness. In certain embodiments, at least aportion of the staples of the plurality of staples can include uniformstaples legs. In other embodiments, at least a portion of the staples ofthe plurality of staples can include non-uniform staple legs.

The plurality of repeating unit cells can have a variety ofconfigurations. For example, in some embodiments, the plurality ofrepeating unit cells can include a triply periodic minimal surfacestructure. In other embodiments, the plurality of repeating unit cellscan include a Schwarz-P structure.

In some embodiments, the adjunct while under an applied stress in arange of 30 kPa to 90 kPa, can be configured to undergo a strain in arange of 0.1 to 0.9. In other embodiments, the strain can be in therange of 0.1 to 0.7.

In another exemplary embodiment, a stapling assembly includes acartridge having a first longitudinal row of first staples disposedtherein, the first staples being configured to be deployed into tissue,and a non-fibrous adjunct formed of at least one fused bioabsorbablepolymer and configured to be releasably retained on the cartridge suchthat the adjunct can be attached to tissue by the staples in thecartridge, the adjunct comprises a lattice structure having a firstlongitudinal row of first repeating unit cells, each unit cell having anon-uniform thickness such that first and second staples legs of thefirst staples advance through different portions of the adjunct withdifferent relative thicknesses as the first staples are deployed intotissue.

The staples can have a variety of configurations. For example, in someembodiments, the cartridge can include an amount of the first staplesthat are greater than an amount of the first repeating unit cells of theadjunct. In other embodiments, the first staples and the first repeatingunit cells can be arranged at the same frequency such that a first legof each first staple aligns with a portion of the adjunct having a firstthickness and a second leg of each first staple aligns with a portion ofthe adjunct having a second thickness that is less than the firstthickness. In certain embodiments, the first leg can have a first heightand the second leg can have a second height that is less than the firstheight. In other embodiments, each first staple can have a base crownextending between the first and second staple legs, in which the basecrown can be non-planar.

The plurality of repeating unit cells can have a variety ofconfigurations. For example, in some embodiments, the plurality ofrepeating unit cells can include a triply periodic minimal surfacestructure. In other embodiments, the plurality of repeating unit cellscan include a Schwarz-P structure.

In some embodiments, the adjunct while under an applied stress in arange of 30 kPa to 90 kPa, can be configured to undergo a strain in arange of 0.1 to 0.9. In other embodiments, the strain can be in therange of 0.1 to 0.7.

BRIEF DESCRIPTION OF THE DRAWINGS

This invention will be more fully understood from the following detaileddescription taken in conjunction with the accompanying drawings, inwhich:

FIG. 1 is a perspective view of one exemplary embodiment of aconventional surgical stapling and severing instrument;

FIG. 2A is a top view of a staple cartridge for use with the surgicalstapling and severing instrument of FIG. 1 ;

FIG. 2B is a side view of the staple cartridge of FIG. 2A;

FIG. 2C is a perspective view of a portion of a tissue-contactingsurface of the staple cartridge of FIG. 2A;

FIG. 3 is a side view of a staple in an unfired (pre-deployed)configuration that can be disposed within the staple cartridge of thesurgical cartridge assembly of FIG. 4 ;

FIG. 4 is a perspective view of a knife and firing bar (“E-beam”) of thesurgical stapling and severing instrument of FIG. 1 ;

FIG. 5 is a perspective view of a wedge sled of a staple cartridge ofthe surgical stapling and severing instrument of FIG. 1 ;

FIG. 6A is a longitudinal cross-sectional view of an exemplaryembodiment of a surgical cartridge assembly having a compressiblenon-fibrous adjunct attached to a top or deck surface of a staplecartridge;

FIG. 6B is a longitudinal cross-sectional view of a surgical endeffector having an anvil pivotably coupled to an elongate staple channeland the surgical cartridge assembly of FIG. 6A disposed within andcoupled to the elongate staple channel, showing the anvil in a closedpositon without any tissue between the anvil and the adjunct;

FIG. 7 is a partial-schematic illustrating the adjunct of FIGS. 6A-6B ina tissue deployed condition;

FIG. 8A is a perspective view of another exemplary embodiment ofcompressible non-fibrous adjunct;

FIG. 8B is a side view of the adjunct of FIG. 8A;

FIG. 8C is a top view of the adjunct of FIG. 8A;

FIG. 8D is a cross-sectional view of the adjunct of FIG. 8C taken atline 8D-8D;

FIG. 8E is a cross-sectional view of the adjunct of FIG. 8C taken atline 8E-8E;

FIG. 8F is a magnified view of a portion of the adjunct of FIG. 8C takenat 8F;

FIG. 8G is a partial-schematic illustrating the adjunct of FIG. 8A in atissue deployed state;

FIG. 9A is a side view of a single unit cell of the adjunct of FIG. 8A;

FIG. 9B is a perspective view of the single unit cell of FIG. 9A;

FIG. 10A is a schematic illustration of an exemplary unit cell in aprecompressed state;

FIG. 10B is a schematic illustration of the unit cell of FIG. 10A in afirst compressed state;

FIG. 10C is a schematic illustration of the unit cell of FIG. 10A in asecond compressed state;

FIG. 10D is a schematic illustration of the unit cell of FIG. 10A in adensified state;

FIG. 11 is a schematic illustration of the relationship between thestates of the unit cell of FIG. 10A-10D and the stress-strain curve ofthe resulting compressible non-fibrous adjunct;

FIG. 12A is top view of an exemplary embodiment of a compressiblenon-fibrous adjunct formed of repeating unit cells of an embodiment of amodified Schwarz-P structure;

FIG. 12B is top view of an exemplary embodiment of a compressiblenon-fibrous adjunct formed of repeating unit cells of another embodimentof a modified Schwarz-P structure;

FIG. 12C is top view of an exemplary embodiment of a compressiblenon-fibrous adjunct formed of repeating unit cells of another embodimentof a modified Schwarz-P structure;

FIG. 12D is top view of an exemplary embodiment of a compressiblenon-fibrous adjunct formed of repeating unit cells of another embodimentof a modified Schwarz-P structure;

FIG. 13A is a perspective view of another exemplary embodiment of asingle unit cell;

FIG. 13B is a top down view of an exemplary embodiment of a compressiblenon-fibrous adjunct formed of repeating unit cells of FIG. 13A;

FIG. 14A is a perspective view of another exemplary embodiment of asingle unit cell;

FIG. 14B is a top down view of an exemplary embodiment of a compressiblenon-fibrous adjunct formed of repeating unit cells of FIG. 14A;

FIG. 15A is a perspective view of another exemplary embodiment of asingle unit cell;

FIG. 15B is a top down view of an exemplary embodiment of a compressiblenon-fibrous adjunct formed of repeating unit cells of FIG. 15A;

FIG. 16A is a perspective view of another exemplary embodiment of asingle unit cell;

FIG. 16B is a top down view of an exemplary embodiment of a compressiblenon-fibrous adjunct formed of repeating unit cells of FIG. 16A;

FIG. 17A is a perspective view of another exemplary embodiment of acompressible non-fibrous adjunct;

FIG. 17B is a cross-sectional view of the adjunct of FIG. 17A taken atline 17B-17B;

FIG. 17C is a cross-sectional view of the adjunct of FIG. 17A taken atline 17C-17C;

FIG. 18 is a perspective view of another exemplary embodiment of acompressible non-fibrous adjunct disposed on a staple cartridge;

FIG. 19A is a perspective view of another exemplary embodiment of acompressible non-fibrous adjunct having a channel attachment;

FIG. 19B is a cross-sectional view of the adjunct of FIG. 19A taken atline 19B-19B;

FIG. 20 is a partial perspective of another exemplary embodiment of acompressible non-fibrous adjunct having a channel attachment;

FIG. 21 is a partial perspective view of another exemplary embodiment ofa compressible non-fibrous adjunct having a channel attachment;

FIG. 22A is a partial exploded perspective view of an exemplaryembodiment of a stapling assembly having a compressible non-fibrousadjunct releasably retained on a staple cartridge, each withcorresponding edge attachment features;

FIG. 22B is a magnified cross-sectional view of a portion of thestapling assembly taken at line 22B-22B, showing two edge attachmentfeatures prior to engagement;

FIG. 22C is cross-sectional view of the portion of the stapling assemblyof FIG. 22B, showing the two edge attachment features engaged;

FIG. 23A is perspective view of another exemplary embodiment of staplingassembly having a compressible non-fibrous adjunct releasably retainedon a staple cartridge, each with corresponding edge attachment features,showing the edge attachment features engaged;

FIG. 23B is a magnified view of a portion of the stapling assembly ofFIG. 23B;

FIG. 24 is a perspective view of another exemplary embodiment of astaple cartridge having end attachment features;

FIG. 25 is a perspective view of another exemplary embodiment of astaple cartridge having end attachment features;

FIG. 26A is a exploded view of another exemplary embodiment of astapling assembly having a staple cartridge and a compressiblenon-fibrous adjunct with attachment features releasably retainedthereon;

FIG. 26B is a cross-sectional view of the stapling assembly of FIG. 26Ataken at line 26B-26B;

FIG. 26C is a cross-sectional view of the stapling assembly of FIG. 26Ataken at line 26C-26C;

FIG. 27 is a partial cross-sectional view of another exemplaryembodiment of a stapling assembly having a compressible non-fibrousadjunct releasably retained on a staple cartridge;

FIG. 28A is a partial cross-sectional view of another exemplaryembodiment of a stapling assembly having a compressible non-fibrousadjunct releasably retained on a staple cartridge;

FIG. 28B is a partial-schematic illustrating the adjunct of FIG. 28A ina tissue deployed condition;

FIG. 29 is a partial cross-sectional view of another exemplaryembodiment of a stapling assembly having a compressible non-fibrousadjunct releasably retained on a staple cartridge;

FIG. 30A is a perspective view of another exemplary embodiment of acompressible non-fibrous adjunct;

FIG. 30B is a front plan view of the adjunct of FIG. 30A;

FIG. 31A is a perspective view of one embodiment of a compressiblenon-fibrous adjunct;

FIG. 31B is a perspective view of a single unit cell of the adjunct ofFIG. 31A;

FIG. 31C is a side view of the unit cell of FIG. 31B;

FIG. 31D is an alternate side view of the unit cell of FIGS. 31B-31C;

FIG. 32A is a perspective view of another exemplary embodiment of acompressible non-fibrous adjunct;

FIG. 32B is a perspective view of a single unit cell of the adjunct ofFIG. 32A;

FIG. 32C is a side view of the unit cell of FIG. 32B;

FIG. 32D is a sectional top view of the unit cell of FIGS. 32B-32C,taken along line 32D-32D of FIG. 32C;

FIG. 33A is a perspective view of another exemplary embodiment of acompressible non-fibrous adjunct;

FIG. 33B is a perspective view of a single unit cell of the adjunct ofFIG. 33A;

FIG. 33C is a side view of the unit cell of FIG. 33B;

FIG. 33D is a sectional top view of the unit cell of FIGS. 33B-33C,taken along line 33D-33D of FIG. 33C;

FIG. 33E is an alternate side view of the unit cell of FIGS. 33B-33C;

FIG. 34A is a perspective view of another exemplary embodiment of acompressible non-fibrous adjunct;

FIG. 34B is a perspective view of a single unit cell of the adjunct ofFIG. 34A;

FIG. 34C is a side view of the unit cell of FIG. 34B;

FIG. 34D is a top view of the unit cell of FIGS. 34B-34C;

FIG. 34E is an alternate side view of the unit cell of FIGS. 34B-34C;

FIG. 35 is a perspective of view of another exemplary embodiment of aunit cell;

FIG. 36 is a perspective of view of another exemplary embodiment of aunit cell;

FIG. 37A is a partially exploded perspective view of another exemplaryembodiment of a stapling assembly having a staple cartridge and acompressible non-fibrous adjunct;

FIG. 37B is a cross-sectional view of a portion of the stapling assemblytaken at line 37B-37B of FIG. 37A;

FIG. 38A is a schematic illustration of the portion of the staplingassembly of FIG. 37B, showing tissue disposed onto the adjunct;

FIG. 38B is a partial-schematic illustrating the adjunct of FIG. 37A ina tissue deployed condition;

FIG. 39A is an exploded view of an exemplary embodiment staplingassembly having a staple cartridge and an adjunct, in which only asecond outer layer of the adjunct is illustrated;

FIG. 39B is a front view of the stapling assembly of FIG. 39A;

FIG. 40 is a perspective view of another exemplary embodiment of astapling assembly having a compressible non-fibrous adjunct releasablyretained on a staple cartridge;

FIG. 41A is a perspective view of another exemplary embodiment of acompressible non-fibrous adjunct;

FIG. 41B is a cross-sectional view of a portion of the adjunct of FIG.41A taken at line 41B-41B and releasably retained on a staple cartridge;

FIG. 41C is a cross-sectional view of a portion of the adjunct of FIG.41A taken at line 41C-41C and releasably retained on a staple cartridge;

FIG. 42A is a perspective view of another exemplary embodiment of acompressible non-fibrous adjunct;

FIG. 42B is a partial-schematic illustrating the adjunct of FIG. 42A ina tissue deployed condition;

FIG. 43A is a perspective view of another exemplary embodiment of acompressible non-fibrous adjunct;

FIG. 43B is a cross-sectional view of the adjunct of FIG. 43A taken atline 43B-43B;

FIG. 44A is cross-sectional view of another exemplary embodiment of acompressible non-fibrous adjunct, showing only a portion of the adjunctreleasably retained on a staple cartridge;

FIG. 44B is a partial-schematic illustrating tissue being clampedbetween an anvil and the portion of the adjunct of FIG. 44A with staplespartially deployed through the adjunct from the staple cartridge;

FIG. 44C is a partial-schematic illustrating the adjunct of FIG. 44A ina tissue deployed condition;

FIG. 45A is a partially exploded perspective view of another exemplaryembodiment of a stapling assembly having a compressible non-fibrousadjunct releasably retained on a staple cartridge;

FIG. 45B is a top down view of a portion of the stapling assembly ofFIG. 45A;

FIG. 45C is a cross-sectional view of the stapling assembly of FIG. 45Btaken at line 45C-45C;

FIG. 46A is a perspective view of another exemplary embodiment of aportion of a stapling assembly having a compressible non-fibrous adjunctreleasably retained on a staple cartridge;

FIG. 46B is a top down view of the portion of the stapling assembly ofFIG. 46A;

FIG. 47A is a cross-sectional front view of an exemplary embodiment of asurgical end effector having an anvil and a stapling assembly, thestapling assembly having a compressible non-fibrous adjunct releasablyretained on a staple cartridge, showing the surgical end effector in aclosed positioned without tissue positioned between the anvil and thestapling assembly;

FIG. 47B is a cross-sectional front view of the surgical end effector ofFIG. 47A, showing tissue clamped between the anvil and the staplingassembly and stapled to the compressible non-fibrous adjunct;

FIG. 47C is a cross-sectional front view of only the stapling assemblyof FIG. 47A;

FIG. 48A is a cross-sectional front view of another exemplary embodimentof a surgical end effector having an anvil and a stapling assembly, thestapling assembly having a compressible non-fibrous adjunct releasablyretained on a staple cartridge, showing the surgical end effector in aclosed positioned without tissue positioned between the anvil and thestapling assembly;

FIG. 48B is a cross-sectional front view of the surgical end effector ofFIG. 48A, showing tissue clamped between the anvil and the staplingassembly and stapled to the compressible non-fibrous adjunct;

FIG. 48C is a cross-sectional front view of only the stapling assemblyof FIG. 48A;

FIG. 49 a perspective view of another exemplary embodiment of acompressible non-fibrous adjunct;

FIG. 50A is a side view of an exemplary embodiment of a surgical endeffector having an anvil and a stapling assembly, the stapling assemblyhaving a compressible non-fibrous adjunct releasably retained on astaple cartridge, showing the surgical end effector in a closedpositioned without tissue positioned between the anvil and the staplingassembly;

FIG. 50B is a side view of the surgical end effector of FIG. 50A,showing tissue clamped between the anvil and the stapling assembly;

FIG. 50C is side view of only the stapling assembly of FIG. 50A;

FIG. 51A is a cross-sectional front view of another exemplary embodimentof a surgical end effector having an anvil and a stapling assembly, thestapling assembly having a compressible non-fibrous adjunct releasablyretained on a staple cartridge, showing the surgical end effector in aclosed positioned without tissue positioned between the anvil and thestapling assembly;

FIG. 51B is a cross-sectional front view of only the compressiblenon-fibrous adjunct of FIG. 51A;

FIG. 52A is a cross-sectional front view of another exemplary embodimentof a surgical end effector having an anvil and a stapling assembly, thestapling assembly having a compressible non-fibrous adjunct releasablyretained on a staple cartridge, showing the surgical end effector in aclosed positioned without tissue positioned between the anvil and thestapling assembly;

FIG. 52B is a cross-sectional front magnified view of only a portion ofthe stapling assembly of FIG. 52A;

FIG. 53 a cross-sectional view of a portion of another exemplaryembodiment of a compressible non-fibrous adjunct releasably retained ona staple cartridge;

FIG. 54 a cross-sectional view of a portion of another exemplaryembodiment of a compressible non-fibrous adjunct releasably retained ona staple cartridge, showing only three staples from three staple rows ofthe staple cartridge;

FIG. 55 is a schematic illustration of the stress-strain curves of theadjunct of FIG. 54 at each of the three staple;

FIG. 56 is a graph showing a stress-strain curve of an exemplarycompressible non-fibrous adjunct (Adjunct 1) of Example 9 and 10;

FIG. 57 is a graph showing stress-strain curves of four exemplarycompressible non-fibrous adjuncts (Adjuncts 2-5) of Example 9 and 10;and

FIG. 58 is a graph showing stress-strain curves of six exemplaryembodiments of compressible non-fibrous adjuncts of Example 11.

DETAILED DESCRIPTION

Certain exemplary embodiments will now be described to provide anoverall understanding of the principles of the structure, function,manufacture, and use of the adjuncts, systems, and methods disclosedherein. One or more examples of these embodiments are illustrated in theaccompanying drawings. Those skilled in the art will understand that theadjuncts, systems, and methods specifically described herein andillustrated in the accompanying drawings are non-limiting exemplaryembodiments and that the scope of the present invention is definedsolely by the claims. The features illustrated or described inconnection with one exemplary embodiment may be combined with thefeatures of other embodiments. Such modifications and variations areintended to be included within the scope of the present invention.

Surgical stapling assemblies and methods for manufacturing and using thesame are provided. In general, a surgical stapling assembly can includea staple cartridge having staples disposed therein and a compressible,bioabsorbable non-fibrous adjunct configured to be releasably retainedon the staple cartridge. In some embodiments, the non-fibrous adjunctcan be formed from a matrix that includes at least one fusedbioabsorbable polymer, and thus it can be three-dimensionally printed.In other embodiments, the non-fibrous adjunct can be partially or whollyformed via any suitable non-additive manufacturing processes, such asinjection molding, foaming, and forming processes as understood by aperson skilled in the art. As discussed herein, the various adjunctsprovided can be configured to compensate for variations in tissueproperties, such as variations in tissue thickness, and/or to promotetissue ingrowth when the adjuncts are stapled to tissue. For example,the adjuncts can be configured such that, while under an applied stressin a range of about 30 kPa to 90 kPa, the adjunct undergoes a strain ina range of about 0.1 (10% deformation) to 0.9 (90 percent deformation).That is, the adjuncts described herein can be configured to deform fromabout 10% to 90% when the adjunct is under an amount of stress that isbetween and/or including about 30 kPa to 90 kPa, e.g., when the adjunctis in a tissue-deployed state.

An exemplary stapling assembly can include a variety of features tofacilitate application of a surgical staple, as described herein andillustrated in the drawings. However, a person skilled in the art willappreciate that the stapling assembly can include only some of thesefeatures and/or it can include a variety of other features known in theart. The stapling assemblies described herein are merely intended torepresent certain exemplary embodiments. Moreover, while the adjunctsare described in connection with surgical staple cartridge assemblies,the adjuncts can be used in connection with staple reloads that are notcartridge based or any type of surgical instrument.

FIG. 1 illustrates an exemplary surgical stapling and severing device100 suitable for use with an implantable adjunct. The illustratedsurgical stapling and severing device 100 includes a staple applyingassembly 106 or end effector having an anvil 102 that is pivotablycoupled to an elongate staple channel 104. As a result, the stapleapplying assembly 106 can move between an open position, as shown inFIG. 1 , and a closed position in which the anvil 102 is positionedadjacent to the elongate staple channel 104 to engage tissuetherebetween. The staple applying assembly 106 can be attached at itsproximal end to an elongate shaft 108 forming an implement portion 110.When the staple applying assembly 106 is closed, or at leastsubstantially closed, (e.g., the anvil 102 moves from the open positionin FIG. 1 toward the elongate staple channel) the implement portion 110can present a sufficiently small cross-section suitable for insertingthe staple applying assembly 106 through a trocar. While the device 100is configured to staple and sever tissue, surgical devices configured tostaple but not sever tissue are also contemplated herein.

In various instances, the staple applying assembly 106 can bemanipulated by a handle 112 connected to the elongate shaft 108. Thehandle 112 can include user controls such as a rotation knob 114 thatrotates the elongate shaft 108 and the staple applying assembly 106about a longitudinal axis of the elongate shaft 108, and a closuretrigger 116 which can pivot relative to a pistol grip 118 to close thestaple applying assembly 106. A closure release button 120 can beoutwardly presented on the handle 112 when the closure trigger 116 isclamped such that the closure release button 120 can be depressed tounclamp the closure trigger 116 and open the staple applying assembly106, for example.

A firing trigger 122, which can pivot relative to the closure trigger116, can cause the staple applying assembly 106 to simultaneously severand staple tissue clamped therein. In various instances, multiple firingstrokes can be employed using the firing trigger 122 to reduce theamount of force required to be applied by the surgeon's hand per stroke.In certain embodiments, the handle 112 can include one or more rotatableindicator wheels such as, for example, rotatable indicator wheel 124which can indicate the firing progress. A manual firing release lever126 can allow the firing system to be retracted before full firingtravel has been completed, if desired, and, in addition, the firingrelease lever 126 can allow a surgeon, or other clinician, to retractthe firing system in the event that the firing system binds and/orfails.

Additional details on the surgical stapling and severing device 100 andother surgical stapling and severing devices suitable for use with thepresent disclosure are described, for example, in U.S. Pat. No.9,332,984 and in U.S. Patent Publication No. 2009/0090763, thedisclosures of which are incorporated herein by reference in theirentireties. Further, the surgical stapling and severing device need notinclude a handle, but instead can have a housing that is configured tocouple to a surgical robot, for example, as described in U.S. PatentPublication No. 2019/0059889, the disclosure of which is incorporatedherein by reference in its entirety.

As further shown in FIG. 1 , a staple cartridge 200 can be utilized withthe instrument 100. In use, the staple cartridge 200 is placed withinand coupled to the elongate staple channel 104. While the staplecartridge 200 can have a variety of configurations, in this illustratedembodiment, the staple cartridge 200, which is shown in more detail inFIGS. 2A-2B, has a proximal end 202 a and a distal end 202 b with alongitudinal axis (L_(C)) extending therebetween. As a result, when thestaple cartridge 200 is inserted into the elongate staple channel 104(FIG. 1 ), the longitudinal axis (L_(C)) aligns with the longitudinalaxis (L_(S)) of the elongate shaft 108. Further, the staple cartridge200 includes a longitudinal slot 210 defined by two opposing walls 210a, 210 b and configured to receive at least a portion of a firing memberof a firing assembly, like firing assembly 400 in FIG. 4 , as discussedfurther below. As shown, the longitudinal slot 202 extends from theproximal end 202 a toward the distal end 202 b of the staple cartridge200. It is also contemplated herein that in other embodiments, thelongitudinal slot 202 can be omitted.

The illustrated staple cartridge 200 includes staple cavities 212, 214defined therein, in which each staple cavity 212, 214 is configured toremovably house at least a portion of a staple (not shown). The number,shape, and position of the staple cavities can vary and can depend atleast on the size and shape of the staples to be removably disposedtherein. In this illustrated embodiment, the staple cavities arearranged in two sets of three longitudinal rows, in which the first setof staple cavities 212 is positioned on a first side of the longitudinalslot 210 and the second set of staple cavities 214 is positioned on asecond side of the longitudinal slot 210. On each side of thelongitudinal slot 210, and thus for each set of rows, a firstlongitudinal row of staple cavities 212 a, 214 a extends alongside thelongitudinal slot 210, a second row of staple cavities 212 b, 214 bextends alongside the first row of staple cavities 212 a, 214 b, and athird row of staple cavities 212 c, 214 c extends alongside the secondrow of staple cavities 212 b, 214 b. For each set of rows, the first rowof staple cavities 212 a, 214 b, the second row of staple cavities 212b, 214 b, and the third row of staple cavities 214 c, 214 c are parallelto one another and the longitudinal slot 210. Further, as shown, foreach set of rows, the second row of staple cavities 212 b, 214 b isstaggered with respect to the first and third rows of staple cavities212 a, 212 c, 214 a, 214 c. In other embodiments, the staple cavity rowsin each set 212, 214 are not parallel to one another and/or thelongitudinal slot 210.

The staples releasably stored in the staple cavities 212, 214 can have avariety of configurations. An exemplary staple 300 that can bereleasably stored in each of the staple cavities 212, 214 is illustratedin FIG. 3 in its unfired (pre-deployed, unformed) configuration. Theillustrated staple 300 includes a crown (base) 302 and two legs 304extending from each end of the crown 302. In this embodiment, the crown302 extends in a linear direction and the staple legs 304 have the sameunformed height, whereas in other embodiments, the crown can be a stepup crown, e.g., like crown 2804 c, 2806 c, 2808 c in FIG. 28A, and/orthe staple legs can have different unformed heights (see FIG. 29 ).Further, prior to the staples 300 being deployed, the staple crowns 302can be supported by staple drivers that are positioned within the staplecartridge 200 and, concurrently, the staple legs 304 can be at leastpartially contained within the staple cavities 212, 214. Further, thestaple legs 304 can extend beyond a top surface, like top surface 206,of the staple cartridge 200 when the staples 300 are in their unfiredpositions. In certain instances, as shown in FIG. 3 , the tips 306 ofthe staple legs 304 can be pointed and sharp which can incise andpenetrate tissue.

In use, staples 300 can be deformed from an unfired position into afired position such that the staple legs 304 move through the staplecavities 212, 214, penetrate tissue positioned between the anvil 102 andthe staple cartridge 200, and contact the anvil 102. As the staple legs304 are deformed against the anvil 102, the legs 304 of each staple 300can capture a portion of the tissue within each staple 300 and apply acompressive force to the tissue. Further, the legs 304 of each staple300 can be deformed downwardly toward the crown 302 of the staple 300 toform a staple entrapment area in which the tissue can be capturedtherein. In various instances, the staple entrapment area can be definedbetween the inner surfaces of the deformed legs and the inner surface ofthe crown of the staple. The size of the entrapment area for a staplecan depend on several factors such as the length of the legs, thediameter of the legs, the width of the crown, and/or the extent in whichthe legs are deformed, for example.

In some embodiments, all of the staples disposed within the staplecartridge 200 can have the same unfired (pre-deployed, unformed)configuration. In other embodiments, the staples can include at leasttwo groups of staples each having a different unfired (pre-deployed,unformed) configuration, e.g., varying in height and/or shape, relativeto one another, etc. For example, the staple cartridge 200 can include afirst group of staples having a first height disposed within the firstrow of staple cavities 212 a, 214 a, a second group of staples having asecond height disposed within the second row of staple cavities 212 b,214 b, and a third group of staples having a third height disposedwithin the third row of staple cavities 212 c, 214 c. In someembodiments, the first, second, and third heights can be different, inwhich the third height is greater than the first height and the secondheight. In other embodiments, the first and second heights are the same,but the third height is different and greater than the first height andthe second height. A person skilled in the art will appreciate thatother combinations of staples are contemplated herein.

Further, the staples can include one or more external coatings, e.g., asodium stearate lubricant and/or an antimicrobial agent(s). Theantimicrobial agent(s) can be applied to the staples as its own coatingor incorporated into another coating, such as a lubricant. Non-limitingexamples of suitable antimicrobial agents include5-Chloro-2-(2,4-dichlorophenoxy)phenol, chlorhexidine, silverformulations (e.g., nano-crystalline silver), lauric arginate ethylester (LAE), octenidine, polyhexamethylene biguanide (PHMB),taurolidine, lactic acid, citric acid, acetic acid, and their salts.

Referring back to FIGS. 2A-2B, the staple cartridge 200 extends from atop surface or deck surface 206 to a bottom surface 208, in which thetop surface 206 is configured as a tissue-facing surface and the bottomsurface 208 is configured as a channel-facing surface. As a result, whenthe staple cartridge 200 is inserted into the elongate staple channel104, as shown in FIG. 1 , the top surface 206 faces the anvil 102 andthe bottom surface 208 (obstructed) faces the elongate staple channel104.

In some embodiments, the top surface 206 can include surface featuresdefined therein. For example, the surface features can be recessedchannels defined within the top surface 206. As shown in more detail inFIG. 2C, a first recessed channel 216 surrounds each first staple cavity212 a, 214 a. Each first recessed channel 216 is defined by asubstantially triangular wall 216 a having a vertex pointing proximally,a vertex pointing distally, and a vertex pointing laterally outwardly.Further, each first recessed channel 216 includes a first floor 206 awhich is at a first height from the top surface 206. A second recessedchannel 218 surrounds each second staple cavity 212 b, 214 b. Eachsecond recessed channel 218 is defined by a wall 218 a which issubstantially diamond-shaped comprising a vertex pointing proximally, avertex pointing distally, a vertex pointing laterally inwardly, and avertex pointing laterally outwardly relative to the longitudinal axis.Further, each second recessed channel 218 includes a second floor 206 bwhich is a second height from the top surface 206. A third recessedchannel 220 surrounds each third staple cavity 212 c, 214 c. Each thirdrecessed channel 220 is defined by a substantially triangular wall 220 acomprising a vertex pointing proximally, a vertex pointing distally, anda vertex pointing laterally inwardly relative to the longitudinal axis.Further, each third recessed channel 220 includes a third floor 206 cwhich is a third height from the top surface 206. In some embodiments,the first height of the first recessed channels 216, the second heightof the second recessed channels 218, and the third height of the thirdrecessed channels 220 can have the same height. In other instances, thefirst height, the second height, and/or the third height can bedifferent. Additional details on the surface features and otherexemplary surface features can be found in U.S. Publication No.2016/0106427, which is incorporated by reference herein in its entirety.Further, as will be discussed in more detail below, these recessedchannels 216, 218, 220 can be used to interact with an adjunct, likeadjunct 2600 in FIGS. 26A-26C, that the adjunct can be releasablyretained to the top surface of cartridge prior to staple deployment.

With reference to FIGS. 4 and 5 , a firing assembly such as, forexample, firing assembly 400, can be utilized with a surgical staplingand severing device, like device 100 in FIG. 1 . The firing assembly 400can be configured to advance a wedge sled 500 having wedges 502configured to deploy staples from the staple cartridge 200 into tissuecaptured between an anvil, like anvil 102 in FIG. 1 , and a staplecartridge, like staple cartridge 200 in FIG. 1 . Furthermore, an E-beam402 at a distal portion of the firing assembly 400 may fire the staplesfrom the staple cartridge. During firing, the E-beam 402 can also causethe anvil to pivot towards the staple cartridge, and thus move thestaple applying assembly from the open position towards a closedposition. The illustrated E-beam 402 includes a pair of top pins 404, apair of middle pins 406, which may follow a portion 504 of the wedgesled 500, and a bottom pin or foot 408. The E-beam 402 can also includea sharp cutting edge 410 configured to sever the captured tissue as thefiring assembly 400 is advanced distally, and thus towards the distalend of the staple cartridge. In addition, integrally formed andproximally projecting top guide 412 and middle guide 414 bracketing eachvertical end of the cutting edge 410 may further define a tissue stagingarea 416 assisting in guiding tissue to the sharp cutting edge 410 priorto being severed. The middle guide 414 may also serve to engage and firethe staples within the staple cartridge by abutting a stepped centralmember 506 of the wedge sled 500 that effects staple formation by thestaple applying assembly 106.

In use, the anvil 102 in FIG. 1 can be moved into a closed position bydepressing the closure trigger in FIG. 1 to advance the E-beam 402 inFIG. 4 . The anvil can position tissue against at least the top surface206 of the staple cartridge 200 in FIGS. 2A-2C. Once the anvil has beensuitably positioned, the staples 300 in FIG. 3 disposed within thestaple cartridge can be deployed.

To deploy staples from the staple cartridge, as discussed above, thesled 500 in FIG. 5 can be moved from the proximal end toward a distalend of the cartridge body, and thus, of the staple cartridge. As thefiring assembly 400 in FIG. 4 is advanced, the sled can contact and liftstaple drivers within the staple cartridge upwardly within the staplecavities 212, 214. In at least one example, the sled and the stapledrivers can each include one or more ramps, or inclined surfaces, whichcan co-operate to move the staple drivers upwardly from their unfiredpositions. As the staple drivers are lifted upwardly within theirrespective staple cavities, the staples are advanced upwardly such thatthe staples emerge from their staple cavities and penetrate into tissue.In various instances, the sled can move several staples upwardly at thesame time as part of a firing sequence.

As indicated above, the stapling device can be used in combination witha compressible adjunct. A person skilled in the art will appreciatethat, while adjuncts are shown and described below, the adjunctsdisclosed herein can be used with other surgical instruments, and neednot be coupled to a staple cartridge as described. Further, a personskilled in the art will also appreciate that the staple cartridges neednot be replaceable.

As discussed above, with some surgical staplers, a surgeon is oftenrequired to select the appropriate staples having the appropriate stapleheight for tissue to be stapled. For example, a surgeon will utilizetall staples for use with thick tissue and short staples for use withthin tissue. In some instances, however, the tissue being stapled doesnot have a consistent thickness and thus, the staples cannot achieve thedesired fired configuration for every section of the stapled tissue(e.g., thick and thin tissue sections). The inconsistent thickness oftissue can lead to undesirable leakage and/or tearing of tissue at thestaple site when staples with the same or substantially greater heightare used, particularly when the staple site is exposed tointra-pressures at the staple site and/or along the staple line.

Accordingly, various embodiments of non-fibrous adjuncts are providedthat can be configured to compensate for varying thickness of tissuethat is captured within fired (deployed) staples to avoid the need totake into account staple height when stapling tissue during surgery.That is, the adjuncts described herein can allow a set of staples withthe same or similar heights to be used in stapling tissue of varyingthickness (e.g., from thin to thick tissue) while also, in combinationwith the adjunct, providing adequate tissue compression within andbetween fired staples. Thus, the adjuncts described herein can maintainsuitable compression against thin or thick tissue stapled thereto tothereby minimize leakage and/or tearing of tissue at the staple sites.

Alternatively or in addition, the non-fibrous adjuncts can be configuredto promote tissue ingrowth. In various instances, it is desirable topromote the ingrowth of tissue into an implantable adjunct, to promotethe healing of the treated tissue (e.g., stapled and/or incised tissue),and/or to accelerate the patient's recovery. More specifically, theingrowth of tissue into an implantable adjunct may reduce the incidence,extent, and/or duration of inflammation at the surgical site. Tissueingrowth into and/or around the implantable adjunct may, for example,manage the spread of infections at the surgical site. The ingrowth ofblood vessels, especially white blood cells, for example, into and/oraround the implantable adjunct may fight infections in and/or around theimplantable adjunct and the adjacent tissue. Tissue ingrowth may alsoencourage the acceptance of foreign matter (e.g., the implantableadjunct and the staples) by the patient's body and may reduce thelikelihood of the patient's body rejecting the foreign matter. Rejectionof foreign matter may cause infection and/or inflammation at thesurgical site.

Unlike conventional adjuncts (e.g., adjuncts that are notthree-dimensionally printed, such as foam adjuncts and woven/non-wovenfibrous adjuncts), these non-fibrous adjuncts are three-dimensionally(3D) printed and therefore can be formed with microstructures (units)that are consistent and reproducible. That is, unlike with other methodsof manufacture, 3D printing significantly improves control overmicrostructural features such as placement and connection of elements.As a result, variability in both the microstructure(s) and attendantproperties of the present adjuncts is decreased, as compared toconventional adjuncts. For example, the present adjuncts can bestructured such that they compress a predetermined amount in asubstantially uniform matter. The fine control over the microstructurecan also allow the porosity of the adjuncts to be tailored to enhancetissue ingrowth. The present non-fibrous adjuncts can also be adaptedfor use with a variety of staples and tissue types.

In general, the adjuncts provided herein are designed and positionedatop a staple cartridge, like staple cartridge 200. When the staples arefired (deployed) from the cartridge, the staples penetrate through theadjunct and into tissue. As the legs of the staple are deformed againstthe anvil that is positioned opposite the staple cartridge, the deformedlegs capture a portion of the adjunct and a portion of the tissue withineach staple. That is, when the staples are fired into tissue, at least aportion of the adjunct becomes positioned between the tissue and thefired staple. While the adjuncts described herein can be configured tobe attached to a staple cartridge, it is also contemplated herein thatthe adjuncts can be configured to mate with other instrument components,such as an anvil of a surgical stapler. A person of ordinary skill willappreciate that the adjuncts provided herein can be used withreplaceable cartridges or staple reloads that are not cartridge based.

Methods of Stapling Tissue

FIGS. 6A-6B illustrate an exemplary embodiment of a stapling assembly600 that includes a staple cartridge 602 and an adjunct 604. For sake ofsimplicity, the adjunct 604 is generally illustrated in FIGS. 6A-6B, andvarious structural configurations of the adjunct are described in moredetail below. Aside from the differences described in detail below, thestaple cartridge 602 can be similar to staple cartridge 200 (FIG. 1-3 )and therefore common features are not described in detail herein. Asshown, the adjunct 604 is positioned against the staple cartridge 602.While partially obstructed in FIG. 6 , the staple cartridge 602 includesstaples 606, which can be similar to staple 300 in FIG. 3 , that areconfigured to be deployed into tissue. The staples 606 can have anysuitable unformed (pre-deployed) height. For example, the staples 606can have an unformed height between about 2 mm and 4.8 mm. Prior todeployment, the crowns of the staples can be supported by staple drivers(not shown).

In the illustrated embodiment, the adjunct 604 can be mated to at leasta portion of the top surface or deck surface 608 of the staple cartridge602. In some embodiments, the top surface 608 of the staple cartridge602 can include one or more surface features, like recessed channels216, 218, 220 as shown in FIGS. 2A and 2C. The one or more surfacefeatures can be configured to engage the adjunct 604 to avoidundesirable movements of the adjunct 604 relative to the staplecartridge 602 and/or to prevent premature release of the adjunct 604from the staple cartridge 602. Exemplary surface features are describedin U.S. Patent Publication No. 2016/0106427, which is incorporated byreference herein in its entirety.

FIG. 6B shows the stapling assembly 600 placed within and coupled to theelongate staple channel 610 of surgical end effector 601, which issimilar to surgical end effector 106 in FIG. 1 . The anvil 612 ispivotally coupled to the elongate staple channel 610 and is thusmoveable between open and closed positions relative to the elongatestaple channel 610, and thus the staple cartridge 602. The anvil 612 isshown in a closed position in FIG. 6B, and illustrates a tissue gapT_(G) created between the staple cartridge 602 and the anvil 612. Morespecifically, the tissue gap T_(G) is defined by the distance betweenthe tissue-compression surface 612 a of the anvil 612 (e.g., thetissue-engaging surface between staple forming pockets in the anvil) andthe tissue-contacting surface 604 a of the adjunct 604. In thisillustrated embodiment, both the tissue-compression surface 612 a of theanvil 612 and the tissue-contacting surface 604 a of the adjunct 604 isplanar, or substantially planar (e.g., planar within manufacturingtolerances). As a result, when the anvil 612 is in a closed position, asshown in FIG. 6B, the tissue gap T_(G) is generally uniform (e.g.,nominally identical within manufacturing tolerances) when no tissue isdisposed therein. In other words, the tissue gap T_(G) is generallyconstant (e.g., constant within manufacturing tolerances) across the endeffector 601 (e.g., in the y-direction). In other embodiments, thetissue-compression surface of the anvil can include a stepped surfacehaving longitudinal steps between adjacent longitudinal portions, andthus create a stepped profile (e.g., in the y-direction). In suchembodiments, the tissue gap T_(G) can be varied.

The adjunct 604 is compressible to permit the adjunct to compress tovarying heights to thereby compensate for different tissue thicknessthat are captured within a deployed staple. The adjunct 604 has anuncompressed (undeformed), or pre-deployed, height and is configured todeform to one of a plurality of compressed (deformed), or deployed,heights. For example, the adjunct 604 can have an uncompressed heightwhich is greater than the fired height of the staples 606 disposedwithin the staple cartridge 602 (e.g., the height (H) of the firedstaple 606 a in FIG. 7 ). That is, the adjunct 604 can have anundeformed state in which a maximum height of the adjunct 604 is greaterthan a maximum height of a fired staple (e.g., a staple that is in aformed configuration). In one embodiment, the uncompressed height of theadjunct 604 can be about 10% taller, about 20% taller, about 30% taller,about 40% taller, about 50% taller, about 60% taller, about 70% taller,about 80% taller, about 90% taller, or about 100% taller than the firedheight of the staples 606. In certain embodiments, the uncompressedheight of the adjunct 604 can be over 100% taller than the fired heightof the staples 606, for example.

In use, once the surgical stapling and severing device, like device 100in FIG. 1 , is directed to the surgical site, tissue is positionedbetween the anvil 612 and the stapling assembly 600 such that the anvil612 is positioned adjacent to a first side of the tissue and thestapling assembly 600 is positioned adjacent to a second side of thetissue (e.g., the tissue can be positioned against the tissue-contactingsurface 604 a of the adjunct 604). Once tissue is positioned between theanvil 612 and the stapling assembly 600, the surgical stapler can beactuated, e.g., as discussed above, to thereby clamp the tissue betweenthe anvil 612 and the stapling assembly 600 (e.g., between thetissue-compression surface 612 a of the anvil 612 and thetissue-contacting surface 604 a of the adjunct 604) and to deploystaples from the cartridge through the adjunct and into the tissue tostaple and attach the adjunct to the tissue.

As shown in FIG. 7 , when the staples 606 are fired, tissue (T) and aportion of the adjunct 604 are captured by the fired (formed) staples606 a. The fired staples 606 a each define the entrapment area therein,as discussed above, for accommodating the captured adjunct 604 andtissue (T). The entrapment area defined by a fired staple 606 a islimited, at least in part, by a height (H) of the fired staple 606 a.For example, the height of a fired staple 606 a can be about 0.160inches or less. In some embodiments, the height of a first stapled 606 acan be about 0.130 inches or less. In one embodiment, the height of afired staple 606 a can be from about 0.020 inches to 0.130 inches. Inanother embodiment, the height of a fired staple 606 a can be from about0.060 inches to 0.160 inches.

As described above, the adjunct 604 can be compressed within a pluralityof fired staples whether the thickness of the tissue captured within thestaples is the same or different within each fired staple. In at leastone exemplary embodiment, the staples within a staple line, or row canbe deformed such that the fired height is about 2.75 mm, for example,where the tissue (T) and the adjunct 604 can be compressed within thisheight. In certain instances, the tissue (T) can have a compressedheight of about 1.0 mm and the adjunct 604 can have a compressed heightof about 1.75 mm. In certain instances, the tissue (T) can have acompressed height of about 1.50 mm and the adjunct 604 can have acompressed height of about 1.25 mm. In certain instances, the tissue (T)can have a compressed height of about 1.75 mm and the adjunct 604 canhave a compressed height of about 1.00 mm. In certain instances, thetissue (T) can have a compressed height of about 2.00 mm and the adjunct604 can have a compressed height of about 0.75 mm. In certain instances,the tissue (T) can have a compressed height of about 2.25 mm and theadjunct 604 can have a compressed height of about 0.50 mm. Accordingly,the sum of the compressed heights of the captured tissue (T) and adjunct604 can be equal, or at least substantially equal, to the height (H) ofthe fired staple 606 a.

Further, most structures typically behave in a way in which strain(deformation) of the material increases as stress exerted on thematerial increases. For surgical stapling, however, it is desired thatstrain of the adjunct increase over a relatively narrow stress range,and therefore as discussed in more detail below, the adjuncts describedherein can be structured in such a way so that they can exhibit a flator moderately sloped “stress plateau.” In general, a stress plateau is aregime in the stress-strain curve of a cellular material uponcompression that corresponds to progressive cell collapse by elasticbuckling, and depends on the nature of the solid from which the materialis made. That is, when a given structure deforms under compression, thestrain can increase without a substantial increase in stress, andtherefore leads to a stress plateau, thereby advantageously delayingdensification (e.g., solid height) of the structure. As a result, theadjuncts described herein can be designed to undergo compression overextended periods of time throughout a range of stresses that aretypically applied to the adjunct while in a tissue deployed state (e.g.,when the adjunct is stapled to tissue in vivo).

The structure of the adjunct, therefore, can be designed such that whenthe adjunct and tissue are captured within the fired staple, the adjunctcan undergo a strain in a range of about 0.1 to 0.9 while under anapplied stress in a range of about 30 kPa to 90 kPa. When the adjunct isin a tissue deployed state, the applied stress is the stress the stapledtissue is applying against the adjunct. A person skilled in the art willappreciate that the applied stress by the tissue depends on variousstapling conditions (e.g., tissue thickness, height of formed staple,intra-tissue pressure). For example, high blood pressure is typicallyconsidered 210 mmHg, and therefore it would be desirable for the presentadjuncts to withstand an applied stress that is equal to or greater than210 mmHg for a predetermined time period without reaching densification.In other embodiments, the strain can be in a range of about 0.1 to 0.8,of about 0.1 to 0.7, of about 0.1 to 0.6, of about 0.2 to 0.8, of about0.2 to 0.7, of about 0.3 to 0.7, of about 0.3 to 0.8, of about 0.3 to0.9, of about 0.4 to 0.9, of about 0.4 to 0.8, of about 0.4 to 0.7, ofabout 0.5 to 0.8, or of about 0.5 to 0.9. Thus, the adjuncts describedherein can be configured to deform and thus, not reach its solid height,while under a predetermined amount of applied stress.

In order to design an adjunct that is configured to undergo a strain ina range of about 0.1 to 0.9 while under an applied stress of about 30kPa to 90 kPa, one can use the principles of Hooke's law (F=kD). Forexample, knowing the forces (stresses) that will be applied to thetissue deployed adjunct, one can design an adjunct to have apredetermined stiffness (k). The stiffness can be set by tuning thegeometry of the adjunct (e.g., the shape, the wall thickness, theheight, and/or the interconnectivity of the unit cells, e.g., angle andspace between unit cells, and/or diameter of struts of a unit celland/or the interconnectivity of the struts of the unit cell, e.g.,angles and space between the struts). Further, one can design theadjunct to have a maximum amount of compression displacement for aminimum thickness of tissue, e.g., 1 mm, and therefore the length ofdisplacement D can be the combination of a minimum thickness of tissue,e.g., 1 mm, plus a thickness of the adjunct when stapled to tissue for agiven max staple height, e.g., 2.75 mm. By way of example, in oneembodiment, an adjunct can be structured to have a height that isgreater than a maximum formed stapled height of 2.75 mm and to compressto a height of 1.75 mm when stapled to tissue having a minimum thicknessof 1 mm. Therefore, the adjunct can vary in compressibility to maintaina constant length of displacement D such that the stiffness (k) andtotal thickness (D) of captured tissue and adjunct can apply a stress of3 gf/mm² to the captured tissue. It should be noted a person of skilledin the art will appreciate that the foregoing formula can be modified totake into account variations in temperatures, e.g., when the adjunct isbrought from room temperature to body temperature after implantation.Further, this forgoing discussion of Hooke's law represents anapproximation. As such, a person skilled in the art will appreciate thatprinciples of large deformation mechanics (also referred to as finiteelasticity) can be used to obtain more accurate predictions of therelationship between stress and strain through the use of constitutiveequations tailored to the material of interest.

The compressibility profile of the adjunct can therefore be controlledby at least the structural configuration of the unit cells and theinterconnectivity between them. As a result, the structuralconfiguration of the unit cells can be tailored to effect an adjunctwith desirable mechanical properties for stapling tissue. As there is afinite range of intra-tissue pressures, tissue thicknesses, and formedstaple heights, one can determine appropriate geometric structures, andthus unit cells, for the adjunct that can be effective in allowing theadjunct to undergo a desired amount of strain at a substantiallyconstant rate while a desired amount of stress is being applied. Stateddifferently, the structural configuration of the unit cells can bedesigned to produce an adjunct that can be effective in applying asubstantially continuous desired stress to the tissue (e.g., of at least3 gf/mm²) to stapled tissue for a given amount of time over a range ofstapling conditions. That is, as described in more detail below, thepresent adjuncts are formed of compressible materials and aregeometrically configured so as to allow the adjunct to compress tovarious heights in predetermined planes when stapled to tissue. Further,this varied response by the adjunct can also allow the adjunct tomaintain its application of a continuous desired stress to the tissuewhen exposed to fluctuations in intra-tissue pressure that can occurwhen the adjunct is stapled to tissue (e.g., a spike in blood pressure).

Adjuncts

The adjuncts can have a variety of configurations. The adjunctsgenerally include a tissue-contacting surface and a cartridge-contactingsurface with an elongate body (e.g., internal structure) positionedtherebetween. The tissue-contacting surface and/or thecartridge-contacting surface can, in certain embodiments, have astructure that differs from the elongate body so as to formtissue-contacting and cartridge-contacting layers, respectively. Asdescribed in more detail below, the adjunct can have a strut-basedconfiguration, a non-strut based configuration, or a combinationthereof.

Further, each exemplary adjunct is illustrated in partial form (e.g.,not in full-length), and therefore a person skilled in the art willappreciate that the adjunct can be longer in length, e.g., along itslongitudinal axis (L_(A)) as identified in each embodiment. The lengthcan vary based on a length of the staple cartridge or anvil. The widthcan also vary as needed. Further, each exemplary adjunct is configuredto be positioned atop a cartridge or anvil surface such that thelongitudinal axis L of each adjunct is aligned with and extends alongthe longitudinal axis (L_(A)) of the cartridge or anvil. These adjunctsare structured so as to compress when exposed to compressive forces(e.g., stress or load).

The adjuncts described herein can have a variety of average lengths,widths, and thicknesses. For example, in some embodiments, the adjunctcan have an average length in a range of about 20 mm to 100 mm or about40 mm to 100 mm. In other embodiments, the adjunct can have an averagewidth in a range of about 5 mm to 10 mm. In yet other embodiments, theadjunct can have an average thickness in a range of about 1 mm to 6 mm,from about 1 mm to 8 mm, from about 2 mm to 6 mm, or from about 2 mm to8 mm. In one embodiment, an exemplary adjunct can have an average lengthin a range of about 20 mm to 100 mm, an average width from 5 mm to 10mm, and an average thickness from about 1 mm to 8 mm.

The elongate body can be formed of one or more lattice structures eachformed by interconnected unit cells. While the unit cells can have avariety of configurations, in some embodiments, the unit cells can bestrut-less based unit cells, whereas in other embodiments, the unitcells can be strut based unit cells. A strut can be a non-hollow rod orbar that is completely, or substantially, formed of solid material. Incertain embodiments, the one or more lattice structures can be formed byinterconnected repeating unit cells. Further, in certain embodiments,the elongate body can include at least one lattice structure formed ofstrut-less based unit cells and at least one lattice structure formed ofstrut based unit cells (see FIG. 54 ).

Each lattice structure extends from a first surface (e.g., a topsurface) to a second surface (e.g., a bottom surface). Depending on theoverall structural configuration of the adjunct, at least a portion ofthe first surface of at least one lattice structure can serve as atissue-contacting surface of the adjunct, and at least a portion of thesecond surface of at least one lattice structure can serve as acartridge-contacting surface of the adjunct. A person skilled in the artwill appreciate that each lattice structure can have additionaltissue-contacting surfaces (e.g., one or more lateral side surfacesrelative to the top surface).

In certain embodiments, an adjunct can include a tissue-contacting layerthat is disposed on at least a portion of the first surface of at leastone lattice structure of the internal structure. The tissue-contactinglayer has a thickness that extends between a first surface (e.g., a topsurface) to a second surface (e.g., a bottom surface). As a result, thefirst surface of the tissue-contacting layer, alone or in combinationwith at least a portion of the first surface of at least one latticestructure, can function as the tissue-contacting surface of theresulting adjunct. The tissue-contacting layer can have a variety ofconfigurations. For example, in some embodiments, the tissue-contactinglayer is in the form of a lattice structure formed of interconnectingrepeating cells that can differ from the lattice structure(s) of theelongate body, whereas in other embodiments, the tissue-contacting layeris in the form of a film.

Alternatively, or in addition, the adjunct can include acartridge-contacting layer that is disposed on at least a portion of thesecond surface of at least one lattice structure. Thecartridge-contacting layer can have a thickness that extends from afirst surface (e.g., a top surface) to a second surface (e.g., a bottomsurface). As a result, the second surface of the cartridge-contactinglayer, alone or in combination with at least a portion of the secondsurface of at least one lattice structure, can function as thecartridge-contacting surface of the resulting adjunct. Thecartridge-contacting layer can have a variety of configurations. Forexample, in some embodiments, the cartridge-contacting layer is in theform of lattice structure formed of interconnecting repeating cells thatcan differ from the lattice structure(s) of the elongate body, whereasin other embodiments, the cartridge-contacting layer is in the form of afilm. In some embodiments, the film can be a pressure sensitiveadhesive, whereas in other embodiments, the film can include one or moreattachment features extending

Non-Strut Based Adjuncts

As noted above, the adjuncts can include a lattice structure formed ofstrut-less based unit cells (e.g., repeating strut-less based unitcells). Stated differently, in contrast to strut-based unit cells, whichare characterized by the presence of sharp corners or angles,non-strut-based unit cells can be characterized by curved surfaces. Forexample, the unit cells can be based on triply periodic minimal surfaces(TPMS). TPMS is a minimal surface that repeats itself in threedimensions. The term “minimal surface” as used in this descriptionrefers to a minimal surface as known in mathematics. As such, in someembodiments, the unit cell can be a Schwarz structure (e.g., Schwarz-P,Schwarz Diamond), a modified Schwarz structure, a gyroid (e.g., SchoenGyroid) structure, a cosine structure, and a coke-can structure.

As discussed in more detail below, the strut-less based unit cells canhave a variety of structural configurations (e.g., height, width, wallthickness, shape). In some embodiments, the strut-less based unit cellsof the adjunct can be generally uniform (e.g., nominally identicalwithin manufacturing tolerances), whereas in other embodiments, at leastone portion of the strut-less based unit cells of the adjunct can varyin shape and/or dimension relative to the remaining portion(s) of thestrut-based unit cells.

For example, in some embodiments, each of the strut-less based unitcells can have a wall thickness from about 0.05 mm to 0.6 mm. In certainembodiments, the wall thickness can be from about 0.1 mm to 0.3 mm. Inone embodiment, the wall thickness can be about 0.2 mm. In certainembodiments, the wall thickness of all of the strut-less based unitcells of an adjunct can be generally uniform (e.g., nominally identicalwithin manufacturing tolerances). In other embodiments, e.g., where theadjunct is formed of two or more sets of unit cells, each set of unitcells can have a different wall thickness. For example, in oneembodiment, the adjunct can include first repeating unit cells eachhaving a first wall thickness, second repeating unit cells each having asecond wall thickness that is greater than the first wall thickness, andthird repeating unit cells each having a third wall thickness that isgreater than the second wall thickness. Alternatively, or in addition,the first repeating unit cells can have a first height (e.g., themaximum height), a second height (e.g., the maximum height) that isgreater than the first height, and a third height (e.g., the maximumheight) that is greater than the second height.

In some embodiments, each unit cell can have a surface to volume ratioof about 5 to 30. In certain embodiments, each unit cell can have asurface to volume ratio of about 7 to 20.

Schwarz-P Structures

FIGS. 8A-8F is one exemplary embodiment of an adjunct 800 having atissue-contacting surface 802 and a cartridge-contacting surface 804.The adjunct 800 includes interconnected repeating strut-less unit cells810, one of which is shown in more detail in FIGS. 9A-9B. While theadjunct 800 is illustrated as having four longitudinal rows (L₁, L₂, L₃,L₄) each with 20 repeating unit cells 810, a person skilled the art willappreciate that the amount of rows and number unit cells of the adjunctcan depend at least upon the size and shape of the staple cartridgeand/or anvil to which the adjunct will be applied, and therefore, theadjunct is not limited to the number of longitudinal rows and unit cellsillustrated in the figures. Further, while only one type of repeatingstrut-less unit cell is illustrated, in other embodiments, the adjunctcan be formed of a combination of a first repeating strut-less unit celland a second repeating strut-less unit cell that differs from the first,etc.

Given that the adjunct 800 is formed of repeating unit cells 810 havingsubstantially the same structural configuration (e.g., nominallyidentical within manufacturing tolerances), the following discussion iswith respect to one repeating unit cell 810. As shown in FIGS. 9A-9B,the repeating unit cell 810 has a top portion 812, a bottom portion 814,and a middle portion 816 extending therebetween.

In this illustrated embodiment, the repeating unit cell 810 isconfigured as a Schwarz-P structure, and therefore, the surface contourof the unit cell 810 is defined by minimal surfaces. That is, theexternal and internal surfaces 820, 822 of the unit cell 810 are eachdefined by minimal surfaces. As such, in this illustrated embodiment,the external and internal surfaces 820, 822 are generally concave inshape, thereby forming arcuate sides 821 of the unit cell 810. Further,the internal surface 822 defines the internal volume 824 of the unitcell 810. As a result, the unit cell 810 can be characterized as beinghollow. The Schwarz-P minimal surface may be functionally expressed as:cos(x)+cos(y)+cos(z)=0.

The unit cell 810 also includes connecting interfaces 826 that can beused to interconnect the unit cell 810 to other unit cells 810 tothereby form the adjunct 800 shown in FIGS. 8A-8E. In this illustratedembodiment, the unit cell includes six connecting interfaces 826 thatform the six outer-most surfaces of the unit cell 810, e.g., top andbottom outer-most surfaces 827 a, 827 b, left and right outer-mostsurfaces 829 a, 829 b, and front and back outer-most surfaces 831 a, 831b. The top and bottom outer-most surfaces 827 a, 827 b are generallyplanar (e.g., planar within manufacturing tolerances) with respect toeach other and offset in the x-direction, the left and right outer-mostsurfaces 829 a, 829 b are generally planar (e.g., planar withinmanufacturing tolerances) with respect to each other and offset in they-direction, and the front and back outer-most surfaces 831 a, 831 b aregenerally planar (e.g., planar within manufacturing tolerances) withrespect to each other and offset in the z-direction. As such, theoverall outer surface of the unit cell 810 includes planar surfaces,e.g., the outer-most surfaces 827 a, 827 b, 829 a, 829 b, 831 a, 831 band non-planar surfaces, e.g., the external surfaces 820 that extendbetween the connecting interfaces 826). Further, since the adjunct 800is only formed of the repeating unit cells 810, the top portion 812,including the top-most outer surface 812 a, forms the tissue-contactingsurface 802 of the adjunct 800, and the bottom-most outer surface 814 a(e.g., in the x-direction) of the bottom portion 814 of the unit cellsforms the cartridge-contacting surface 804 of the adjunct 800. As aresult, the tissue-contacting surface 802 is formed of planar andnon-planar surfaces.

Further, based on the overall geometry of the repeating unit cells 810and their interconnectivity to each other at corresponding connectinginterfaces 826, the overall outer surface of the resulting adjunct 800is formed of generally planar surfaces (e.g., planar withinmanufacturing tolerances) separated by non-planar surfaces. As shown,the top and bottom outer-most surfaces 850 a, 850 b of the adjunct 800are furthest from the bisector extending within the YZ plane, the leftand right outer-most surfaces 852 a, 852 b of the adjunct 800 arefurthest from the bisector extending within the XZ plane, and the frontand back outer-most surfaces 854 a, 854 b of the adjunct are furthestfrom the bisector extending within the XY plane. Further, as shown, thetop and bottom outer-most surfaces 850 a, 850 b are generally planar(e.g., planar within manufacturing tolerances) with respect to eachother and offset in the x-direction, the left and right outer-mostsurfaces 852 a, 852 b are generally planar (e.g., planar withinmanufacturing tolerances) with respect to each other and offset in they-direction, and the front and back outer-most surfaces 854 a, 854 b aregenerally planar (e.g., planar within manufacturing tolerances) withrespect to each other and offset in the z-direction. As such, theseouter-most surfaces 850 a, 850 b, 852 a, 852 b, 854 a, 854 b form theplanar segments of the outer surface of the adjunct 800. It can beappreciated that the portions of the adjunct 800 that extend betweenthese outer-most surfaces 850 a, 850 b, 852 a, 852 b, 854 a, 854 b,which are defined by the external surfaces 820 of adjacent unit cells810, thereby forming the non-planar surfaces of the outer surface of theadjunct 800.

As further shown, the six connecting interfaces 826 define respectivecircular openings that are in fluid communication with the internalvolume 824 of the unit cell 810. As a result, the unit cell 810 hasopenings in all six Cartesian sides (represented as arrows 1, 2, 3, 4,5, 6 in FIG. 9B). These openings can serve multiple functions, forexample: facilitate connections to adjacent cells; create openings thatcan allow for immediate tissue in-growth when the adjunct is in stapledto tissue; allow drainage of manufacturing materials used in theproduction of the resulting adjunct, e.g., materials used during a 3Dmanufacturing process; allow transfer of bodily fluids easily throughoutthe adjunct; contribute to the mechanical properties of the adjunct,e.g., mechanical properties that create a compression profile thatdelays densification of the adjunct; and/or minimize the solid height ofthe fully compressed adjunct.

Moreover, when the unit cells 810 are interconnected to each other atcorresponding connecting interfaces, e.g., at least two connectinginterfaces, hollow tubular interconnections 828 (e.g., lumens) areformed therebetween, as shown in FIGS. 8D-8E, which allow the internalvolumes 824 of the interconnected unit cells 810 to be in fluidcommunication with each other. As such, a continuous network of channelsor pathways are present within the adjunct. As a result, when theadjunct 800 is stapled to tissue (T), and is in a tissue deployed state,as illustrated in FIG. 8G, one or more fluids, including cells thatenter into the adjunct 800, e.g., through the opening of a connectinginterface 826 a of the top portion 812 of at least one unit cell 810,can therefore migrate throughout the adjunct 800, e.g., throughinterconnected unit cells, when in a tissue deployed state, asillustrated in FIG. 8G, and thus, can ultimately accelerate tissueingrowth within the adjunct 800. That is, while the adjunct 800 is in atissue-deployed state, at least a portion of the hollow tubularinterconnection 828 can at least partially maintain fluid communicationbetween at least a portion or through all of internal volumes of theunit cells 810, and thus encourage cell mobility throughout the adjunct800.

While the hollow tubular interconnections 828 define openings that canhave variety of sizes (e.g., diameters), in some embodiments thediameter of the openings can be from about 100 micrometers to 3500micrometers. For example, the diameter of the openings can be from about100 micrometers to 2500 micrometers or from about 500 micrometers to2500 micrometers. In certain embodiments, the diameter of the openingscan be from about 945 micrometers to 1385 micrometers. In oneembodiment, the diameter of the openings can be greater than 2000micrometers. In certain embodiments, the diameter of all the openings issubstantially the same (e.g., nominally identical within manufacturingtolerances). As used herein, “diameter” of an opening is the largestdistance between any pair of vertices of the opening.

Since the repeating unit cells 810 are interconnected to each other atcorresponding connecting interfaces 826, the adjunct 800 is in the formof a lattice structure having predefined compression areas 830 andpredefined non-compression areas 840, as more clearly shown in FIG. 8C.While the predefined compression areas 830 and predefinednon-compression areas 840 can have a variety of configurations, in thisillustrated embodiment, the predefined compression areas 830 are definedby the unit cells 810, and the predefined non-compression areas 840 arein the form of voids 845 defined between the unit cells 810. In thisembodiment, each void 845 is formed between four adjacent interconnectunit cells 810. For example, void 845 a is defined between the fouradjacent unit cells 810 a, 810 b, 810 c, 810 d, as shown in FIG. 8F.Thus, the space that exists between adjacent unit cells define thepredefined non-compression areas. Stated differently, thenon-compression areas 840 of the adjunct are not defined by the internalvolumes of the unit cells.

As described in more detail below, the structural configuration of therepeating unit cell can allow the unit cell to deform or bucklecontinuously along its height H (see FIG. 9A) at different locationsover a period of time (e.g., until opposing sides of the internalsurface of the cell come into contact with each other) while underapplied stress. As a result, during such time, the unit cell, whileunder an applied stress (e.g., 30 kPa to 90 kPa), can deform or buckleat a rate that is constant, or substantially constant. Stateddifferently, in certain embodiments, the structure of the repeating unitcells can lead to a stress plateau while the adjunct is under an appliedstress, e.g., as schematically illustrated in FIG. 11 .

FIGS. 10A-10D schematically illustrate the compressive behavior of onerepeating unit cell, e.g., unit cell 810 in FIGS. 8A-9B, when under arange of applied stress. In particular, the repeating unit cell 1010 isshown in a pre-compressed (undeformed) state in FIG. 10A, a firstcompressed state FIG. 10B, in which each of the top and bottom portions1012, 1014 of the unit cell 1010 begin to compress toward the middleportion 1016 of the unit cell 1010 causing the middle portion 1016 tobegin deflecting, a second compressed state FIG. 10C, in which themiddle portion 1016 continues to deflect outward, and a densified statein FIG. 10D, in which opposing sides 1018 a, 1018 b of the internalsurface 1018 of the middle portion 1016 come into contact with eachother causing the unit cell 810 to reach its solid height.

The relationship between the undeformed state U (FIG. 10A), compressedstates C1, C2 (FIGS. 10B-10C), and densified state D (FIG. 10D) of therepeating unit cell 1010 and the stress-strain curve of the resultingadjunct is schematically illustrated in FIG. 11 .

The stress-strain response of the adjunct starts with an elasticdeformation (bending) characterized by the Young's modulus, e.g., as therepeating unit starts to deform from its uncompressed state towards itsfirst compressed state. This elastic deformation continues until theyield stress is reached. Once the yield stress is reached, a stressplateau can occur, which corresponds to the progressive unit cellcollapse by elastic buckling, e.g., as the repeating unit cell continuesto deform through its first compressed state and second compressedstate. A person skilled in the art will appreciate that the stressplateau depends at least upon the nature of the material from which theunit cell is made. The stress plateau continues until densification,which denotes a collapse of the unit cells throughout the adjunct, e.g.,as the repeating unit cell reaches its densified state, and thus, theadjunct has reached its solid height.

A person skilled in the art will appreciate that the stress-strain curvefor an adjunct depends on various factors, e.g., uncompressed heights,compositional makeup (including material properties), and/or structuralconfiguration. By way of example, Table 1 below illustrates thestress-strain responses for exemplary adjuncts differing only inuncompressed height (UH) and being compressed to a first compressedheight (CH1) of 1.75 mm at an applied stress of 30 kPa, compressed to asecond compressed height (CH2) of 0.75 mm at an applied stress of 90kPa, and compressed to a third compressed height (CH3) of 0.45 mm at anapplied stress of 90 kPa.

TABLE 1 Stress-Strain Relationship for Various Adjunct Heights Strain UHCH1 CH2 CH3 C1 @ C2 @ C3 @ (mm) (mm) (mm) (mm) 30 kPa 90 kPa 90 kPa 21.75 0.75 0.45 0.13 0.63 0.78 2.25 1.75 0.75 0.45 0.22 0.67 0.80 2.51.75 0.75 0.45 0.30 0.70 0.82 2.75 1.75 0.75 0.45 0.36 0.73 0.84 3 1.750.75 0.45 0.42 0.75 0.85 3.25 1.75 0.75 0.45 0.46 0.77 0.86 3.5 1.750.75 0.45 0.50 0.79 0.87

In another embodiment, the repeating strut-less based unit cells can bea modified Schwarz-P structure. For example, the Schwarz-P structure canbe stretched in one or more directions to form a stretched Schwarz-Pstructure, e.g., as illustrated in FIG. 12A. Alternatively or inaddition, in certain embodiments, the wall thickness of the Schwarz-Pstructure can be thinned. For example, as illustrated in FIG. 12B, theSchwarz-P structure is stretched and thinned. In yet another embodiment,as illustrated in FIG. 12C, the Schwarz-P structure can be cropped,e.g., in which the height of the top portion HT (see FIG. 9A) and/orbottom portion H_(B) (see FIG. 9A) of the Schwarz-P structure isdecreased. Alternatively, or in addition to the forgoing exemplarymodifications, additional openings can be added through the walls of theSchwarz-P structure, e.g., as illustrated in FIG. 12D, which can helpwith densification of the resulting adjunct.

The repeating strut-less based unit cells can take the form of otherTPMS structures. For example, as illustrated in 13A, a strut-less basedunit cell 1300 can be formed from a sheet diamond structure having adiamond minimal surface with a Schwarz D surface lattice structure. Thisparticular minimal surface is called a “diamond” because it has twointertwined congruent labyrinths where each has the shape of a tubularversion of a diamond bond structure. The Schwarz D may be functionallyexpressed as:sin(x)sin(y)sin(z)+sin(x)cos(y)cos(z)+cos(x)sin(y)cos(z)+cos(x)cos(y)sin(z)=0.An exemplary adjunct 1310 formed of repeating unit cells 1300, and thussheet diamond structures, is illustrated in FIG. 13B.

In another embodiment, as illustrated in FIG. 14A, a strut-less basedunit cell 1400 can be a gyroid structure. The gyroid minimal surface maybe functionally expressed as:sin(x)cos(y)+sin(y)cos(z)+sin(z)cos(x)=0.An exemplary adjunct 1410 formed of repeating unit cells 1500, and thusgyroid structures, is illustrated in FIG. 14B. In other embodiments, astrut-less based unit cell can be in the form of a cosine structure 1500(FIG. 15A) or in the form of a coke can structure 1600 (FIG. 16A), eachof which is defined by curved minimal surfaces. Exemplary adjuncts 1510,1610 formed of respective repeating unit cells 1500 (cosine structures),1600 (coke can structures) are illustrated in FIGS. 15B and 16B.Edge Conditions

In some embodiments, certain strut-less based unit cells, wheninterconnected to form an adjunct, can form undesirable edge conditionsfor tissue stapling. For example, as tissue slides across the adjunctduring use, the edge conditions can interact with tissue in such a waythat causes at least a portion of the adjunct to prematurely detach fromthe staple cartridge. These edge conditions can be a result of thegeometry (e.g., having generally planar (e.g., planar withinmanufacturing tolerances) and non-planar outer surfaces) andinterconnectivity of the strut-less based unit cells that make up theadjunct. As such, to improve these edge conditions, and thus inhibitpremature detachment of the adjunct, an outer layer having a differentgeometry can be placed atop one or more tissue-contacting surfaces ofthe adjunct.

Referring back to FIGS. 9A-9B, as noted above, a Schwarz-P structure 810has non-planar external surfaces that form the arcuate sides 821 thatextend between the connecting interfaces 826 of the unit cell 810. As aresult, when the Schwarz-P structures 810 are interconnected to form anadjunct, such as adjunct 800 in FIGS. 8A-8F, tissue-contactingsurface(s) can form having planar and non-planar surfaces, liketissue-contacting surface 802 in FIGS. 8A-8B. This is a result of atleast the structural configuration of the top portion 812 of each unitcell 810 (e.g., exposed top-most outer surface 827 a and arcuate sides821 of the top portion 812) and the spaced apart relationship betweenthem. Thus, the edge conditions of the adjunct can be minimized with theapplication of an outer layer having a generally planar (e.g., planarwithin manufacturing tolerances) geometry positioned atop at least oneotherwise tissue-contacting surface of the adjunct, liketissue-contacting surface 802 of adjunct 800 in FIGS. 8A-8F. As aresult, this can lower the tissue loads (applied stress) on the adjunctduring placement of the stapling device. Further, this can ease theattachment requirements between the adjunct and cartridge.

While the outer layer can have a variety of configurations, in someembodiments, the outer layer can be formed of one or more planar arraysof struts (FIGS. 17A-17C), whereas in other embodiments, the outer layercan be in the form of a film (FIG. 18 ).

FIGS. 17A-17C illustrate an exemplary adjunct 1700 having a firstlattice structure 1702 formed of interconnecting repeating unit cells1704 and at least one planar array 1706, 1708. Each unit cell 1704 issimilar to unit cell 810 in FIG. 9A-9B and therefore common features arenot described in detail herein. In this illustrated embodiment, thereare two planar arrays 1706, 1708, in which the first planar array 1706(e.g., in the YZ plane) extends across the top tissue-facing surface1712 of the first lattice structure 1702 and the second planar array1706 (e.g., in the XZ plane) extends across at least one sidetissue-facing surface 1714 of the first lattice structure 1702. In otherembodiments, the first or second planar arrays 1706, 1708 can beomitted. In further embodiments, the adjunct 1700 can include additionalplanar arrays.

While the planar arrays 1706, 1708 can have a variety of configurations,in this illustrated embodiment, the first and second planar arrays 1706,1708 each include longitudinal struts 1716 extending parallel and alongthe longitudinal axis (L_(A)) of the adjunct 1700. While not shown, itis also contemplated that additional struts can be added to the firstand second planar arrays 1706, 1708. For example, in one embodiment, thefirst planar array 1706 and/or second planar array 1708 can includecross struts that extend at an angle relative to the longitudinal axisand intersect the first and/or second longitudinal struts, e.g., therebycreating a repeating X-pattern.

In use, when the adjunct 1700 is releasably retained on a cartridge,such as cartridge 200 in FIGS. 1-2C, the adjunct 1700 overlaps with therows of staples disposed within the cartridge. As a result, the firstplanar array 1706 can add to the ultimate solid height of the adjunct1700, and therefore accelerate densification thereof. However, in aneffort to minimize the impact the first planar array 1706 can have onthe densification, the first planar array 1706 can be designed in such away that it does not overlap with the staple rows. For example, as shownin FIGS. 17A-17C, the first planar array 1706 is divided into fourspaced apart portions 1706 a, 1706 b, 1706 c, 1706 d such that threegaps 1718, 1720, 1722 are formed therebetween and along the longitudinalaxis (L_(A)) for the adjunct 1700. As shown in FIG. 17C, these threegaps 1718, 1720, 1722 can coincide with three staple rows 1724, 1726,1728 of the cartridge (not shown), and therefore, the first planar array1706 will not be captured, or will be minimally captured, by the staplesduring deployment.

As noted above, in some embodiments, an absorbable film can bepositioned on at least a portion of at least one of the non-planartissue-facing surfaces of a lattice structure to thereby substantiallyprevent tissue from causing the adjunct to prematurely detach from thecartridge while the tissue slides across the adjunct. That is, theabsorbable film can minimize edge conditions, and thus decrease thefriction that would otherwise be present on the tissue-contactingsurface(s) of the adjunct.

FIG. 18 illustrates an exemplary embodiment of an adjunct 1800 disposedon a cartridge 1801. The adjunct 1800 includes a lattice structure 1802with an absorbable film 1804 disposed on at least a portion thereof. Thelattice structure 1802, which is similar to the lattice structure ofadjunct 800 in FIG. 8A, is formed of interconnecting repeating unitcells 1806, each of which is similar to unit cell 810 in FIGS. 9A-9B,and therefore common features are not described in detail herein. Asshown, the absorbable film 1804 is disposed on all tissue-facingsurfaces of the lattice structure 1802, which, in this illustratedembodiment, includes a top-tissue facing surface 1808 (e.g., extendingin the x-direction), a first longitudinal side surface 1810 a (e.g.,extending in the z-direction), a second opposing longitudinal sidesurface 1810 b, a first lateral side surface 1812 a (e.g., extending inthe y-direction), and a second opposing lateral side surface(obstructed). In other embodiments, the absorbable film is not disposedon all tissue-facing surfaces of a lattice structure, e.g., the firstlateral side surface and/or the second lateral side surface.

The absorbable film can have a variety of configurations. For example,in some embodiments, the absorbable film is designed to have a thicknessthat nominally impacts densification of an adjunct when the adjunct isunder applied stress and/or formed of one or more materials that helpreduce friction of the tissue-contacting layers for tissue manipulation.In some embodiments, the absorbable film can have a thickness that isless than or equal to about 15 microns, e.g., from about 5 microns to 15microns, or from about 8 microns to 11 microns. In one embodiment, theabsorbable film can be formed of polydioxanone.

Attachment Features

In some embodiments, non-strut-based adjuncts include one or moreattachment features that extend at least partially along the length ofadjunct and that are configured to engage the staple cartridge tothereby retain the adjunct on the cartridge prior to staple deployment.The one or more attachment features can have a variety ofconfigurations. For example, the one or more attachment features can bechannel attachments (FIGS. 19A-21 ), (FIGS. 22A-22B) that are configuredto engage (e.g., press-fit or snap into) the elongate cutting slotformed between opposing longitudinal edges thereof in the staplecartridge, and/or end attachments (FIGS. 24-25 ) that are configured toengage with recessed end channels defined within the staple cartridge.Aside from the differences discussed in detail below, adjuncts 1900,2000, 2100, 2200 are substantially similar to adjunct 800 in FIGS.8A-8F, and therefore common features are not discussed in detail herein.

In some embodiments, the channel attachment can include one or morecompressible members that are structurally configured to be insertedinto a longitudinal slot of a staple cartridge to engage the opposingwalls of the longitudinal slot. In certain embodiments, one or morecompressible members can include a compressible opening that extendstherethrough, e.g., in a longitudinal direction along a length of thecartridge-contacting surface of the adjunct.

FIGS. 19A-19B illustrate an exemplary embodiment of an adjunct 1900 thatincludes a channel attachment 1910 having two compressible members 1912,1914 that are interconnected by at least one common elongated joint1916. While the two compressible members 1912, 1914 can have a varietyof configurations, in this illustrated embodiment, each compressiblemember 1912, 1914 is in the form of an elongated rod having a triangularcross-sectional shape taken across the width thereof (e.g., in they-direction) with a hollow triangular channel 1912 a, 1914 a extendingtherethrough along the length thereof (e.g., in the z-direction). Asshown, the two elongated rods 1912, 1914 are interconnected atcorresponding apexes, thereby forming the elongated joint 1916 thatdefines a central connection region with a narrow thickness (e.g., inthe x-direction). As shown in FIG. 19B, when the adjunct 1900 isdisposed on a cartridge 1901, which is similar to cartridge 200 in FIGS.1-2C, the at least one elongated joint 1916, and thus the centralconnection region, is positioned equidistance from the opposing walls1903 a, 1903 b of the longitudinal slot 1903, as shown in FIG. 19 . As aresult, the central connection region aligns with the advancement lineof the cutting member, and therefore, due to the narrow width of thecentral connection region, the risk of jamming of the cutting member asit advances through the adjunct 1900 can be minimized or prevented. Thatis, the central connection region minimizes the additional adjunctmaterial the cutting member would need to otherwise cut through as itadvances through the longitudinal slot 1903. Further, the hollowtriangular channels 1912 a, 1914 a decrease the amount of material oneach side of the advancement line, which can also minimize the cut edgesof the adjunct from binding to the cutting member as it further advancesthrough the longitudinal slot 1903.

While the overall width W_(C) of the channel attachment 1910 can vary,in this illustrated embodiment, the overall width W_(C) is greater thanthe width W_(L) of the longitudinal slot 1903 (e.g., the distancebetween the two opposing slot walls 1903 a, 1903 b). As a result, whenthe channel attachment 1910 is inserted into the longitudinal slot 1903,the compressible members deform and engage (e.g., compress against)respective slot walls 1903 a, 1903 b due to the outward lateral forcecreated by the hollow triangle channels 1912 a, 1914 a. As such, a pressfit or friction fit is created between the compressible members 1912,1914 and respective slot walls 1903 a, 1903 b of the cartridge 1901.

The channel attachment can have other configurations (e.g., shapesand/or dimensions). For example, as shown in FIG. 20 , adjunct 2000 issimilar to adjunct 800 shown in FIGS. 8A-8X except that adjunct 2000also includes a channel attachment 2010 in the form of an elongatedprojection that extends outward from the cartridge-contacting surface2004 of the adjunct 2000 and is positioned between the two inner rows ofrepeating unit cells 2010 a, 2012 a. The elongated projection 2010 isconfigured to be inserted into a longitudinal slot of a cartridge, likelongitudinal slot 210 of cartridge 200 in FIGS. 2A and 2C.

While the elongated projection 2010 can have a variety ofconfigurations, in this illustrated embodiment, the elongated projection2010 is formed of two compressible longitudinal rods 2010 a, 2010 b withcross rods 2010 c extending therebetween. In some embodiments, the widthof the elongated projection 2010 (e.g., in the y-direction) is greaterthan a width of a longitudinal slot (e.g., the distance between the twoopposing slot walls) of a staple cartridge. As a result, when theelongated projection 2010 is inserted into the longitudinal slot, likelongitudinal slot 210 of cartridge 200 in FIGS. 2A-2C, the twolongitudinal rods are configured to engage (e.g., compress against) theopposing slot walls due to the outward lateral force being created bythe cross rods 2010 c. As such, a press fit or friction fit is formedbetween the elongated projection 2010 and the slot walls of thecartridge.

FIG. 21 illustrates another embodiment of an adjunct 2100 having achannel attachment. Adjunct 2100 is similar to adjunct 2000 shown inFIG. 20 except that the channel attachment is in the form of discreteprojections 2110 (only two are illustrated in FIG. 21 ) that are spacedapart relative to each other along the longitudinal axis L_(A) of theadjunct 2100. While the projections 2110 can have a variety ofconfigurations, in this illustrated embodiment, each projection 2110 isin the form of an annular boss having an oblong shape. In otherembodiments, the projections 2110 can be any other suitable shape and/orvary in size/shape relative to each other. Each annular boss 2110 can beconfigured to be compressible, and in some embodiments, dimensioned suchthat the width of each boss (e.g., in the y-direction) can be greaterthan the width of a longitudinal slot (e.g., the distance between thetwo opposing slot walls) of a staple cartridge, like longitudinal slot210 in cartridge 200 in FIGS. 2A-2C. As a result, when the discreteannular bosses 2110 are inserted into a longitudinal slot of acartridge, their outer surface 2110 a is configured to engage (e.g.,compress against) the opposing slot walls due to the outward radialforce of the annular boss. As such, a press fit or friction fit isformed between the annular bosses 2110 a and the slot walls of thelongitudinal slot.

Alternatively, or in addition, in some embodiments, an adjunct caninclude edge attachment features which are configured to engagecorresponding edge attachment features of an adjunct. For example, asillustrated in FIGS. 22A-22C, an adjunct 2200 can include three sets ofopposing clips 2202 a, 2202 b, 2204 a, 2204 b, 2206 a, 2206 b that eachextend laterally outward and away from opposing outer sides surfaces2200 a, 2200 b of the adjunct 2200. While the three sets of clips 2202a, 2202 b, 2204 a, 2204 b, 2206 a, 2206 b can have a variety ofconfigurations, in this illustrated embodiment, the three sets of clips2202 a, 2202 b, 2204 a, 2204 b, 2206 a, 2206 b each have a hooked shapedconfiguration that engages with respective edge attachment features 2208a, 2208 b, 2210 a, 2210 b, 2212 a, 2212 b of the cartridge 2201. In thisillustrated embodiment, each edge attachment feature 2208 a, 2208 b,2210 a, 2210 b, 2212 a, 2212 b has an inverted L-shaped configurationthereby creating a flange extending laterally outward from the staplecartridge 2201 (only one flange is shown in detail in FIGS. 22B-22C).

The engagement of one clip 2204 a of the adjunct 2200 and one flange2210 a of the cartridge 2201 is illustrated in FIG. 22C. For sake ofsimplicity, the repeating unit cells of adjunct 2200 are omitted. Asshown, the inner surface 2214 a of the end portion 2214 of the clip 2204a engages the outer bottom surface 2216 of the flange 2210 a, therebycausing a portion of the outer surface 2218 of the flange 2210 a to nestagainst a corresponding portion of the inner surface 2220 of the clip2204 a (e.g., male/female engagement). Further, as shown in FIG. 22C,the flange 2210 a is biased outward, and as a result, the portion ofouter surface 2218 of the flange 2210 a is forced against thecorresponding portion of the inner surface 2220 a of the clip 2204 awhen they are engaged.

FIGS. 23A-23B illustrate another embodiment of an adjunct having threesets of opposing clips 2302 a, 2302 b (partially obstructed), 2304 a,2304 b (partially obstructed), 2306 a, 2306 b (partially obstructed)that are configured to engage a corresponding set of opposing receivingmembers 2308, 2310 (partially obstructed), 2312, 2314 (partiallyobstructed), 2316, 2318 (partially obstructed) of the staple cartridge2301.

In this illustrated embodiment, each clip is structurally the same andhas an inverted T-shaped configuration. Further, as shown, each set ofreceiving members is the structurally the same and includes two invertedL-shaped members that are spaced apart and face each other to form at-shaped void therebetween. By way of example, the engagement of oneclip 2302 a with its corresponding set of receiving members 2308 a, 2308b is shown in more detail in FIG. 23B. As shown, the lateral segments2316 a, 2316 b (e.g., extending in the z-direction) of the clip 2302 aare configured to be engage with the respective inner surfaces (only oneinner surface 3118 is illustrated) of each L-shaped member 2308 a, 2308b, and the vertical segment 2320 (e.g., extending in the x-direction) ofthe clip 2302 a is configured to be positioned between the two facingsurfaces (only one facing surface 2322 is illustrated) of the L-shapedmembers 2308 a, 2308 b. As such, the vertical segment 2320 can help withmaintaining the longitudinal alignment of the adjunct 2300 relative tothe staple cartridge 2301, and thus the staples disposed therein (notshown). During use, the vertical segment 2320 can also help preventpremature disengagement of the clip 2302 a from the corresponding set ofreceiving members 2308 a, 2308 b, and thus the adjunct 2300 from thecartridge 2301.

Alternatively, or in addition, in some embodiments, an adjunct caninclude end attachment features, such as opposing proximal and distalsets of bosses that are configured engage (e.g., press fit) intocorresponding proximal and distal sets of recesses defined in the staplecartridge. For example, in one embodiment, an adjunct can haverectangular bosses that are configured to engage proximal and distalsets of rectangular recesses 2402 a, 2402 b, 2404 a, 2404 b of staplecartridge 2400 in FIG. 24 . In another embodiment, an adjunct can havecircular bosses that are configured to engage proximal and distal setsof circular recesses 2502 a, 2502 b, 2504 a, 2504 b of staple cartridge2500 in FIG. 25 .

As noted above, in certain embodiments, the staple cartridge can includesurface features that are in the form of recessed channels, likerecessed channels 216, 218, 220 as shown in FIGS. 2A and 2C. In suchembodiments, the adjunct can be designed to engage with the recessedchannels to effect a releasable attachment mechanism between the adjunctand the staple cartridge, even when the frequency of staples within alongitudinal staple row (e.g., the number of staples per length ofstaple row) are different (e.g., greater) than the frequency of therepeating unit cells within a corresponding longitudinal unit cell row(e.g., the number of unit cells per length of the cell row).

FIGS. 26A-26C illustrate an adjunct 2600 disposed on a staple cartridge2602 which is similar to staple cartridge 200 in FIGS. 2A-2C andtherefore common features are not described in detail herein. The staplecartridge 2602 includes staple cavities that are arranged inlongitudinal rows 2604 a, 2604 b, 2604 c, 2606 a, 2606 b, 2606 c andrecessed channels that surround each staple cavity 2604 a, 2604 b, 2604c, 2606 a, 2606 b, 2606 c. As shown, a first recessed channel 2608surrounds each first staple cavity 2604 a, 2606 a, a second recessedchannel 2610 surrounds each second staple cavity 2604 b, 2606 b, and athird recessed channel 2612 surrounds each third staple cavity 2604 c,2606 c. The first, second, and third recessed channels each include arespective floor 2614, 2616, 2618 which is at a respective height (e.g.,extending in the x-direction) from the top surface 2602 a of the staplecartridge 2602. In this illustrated embodiment, the respective heightsare the same, whereas in other embodiments, the respective heights canbe different.

While the adjunct 2600 can have a variety of configurations, in thisillustrated embodiment, the adjunct 2600 is formed of repeating unitcells 2620 and attachment features 2622 that extend from at least aportion of the plurality of unit cells 2620. The attachment features2622 are each configured to be inserted into and engage with at least aportion of the recessed channels 2608, 2610, 2612 of the staplecartridge 2602 to thereby retain the adjunct 2600 to the cartridge 2602prior to staple deployment.

While the attachment features 2622 can have a variety of configurations,each attachment feature has a different geometry so that the eachattachment feature can engage a respective recessed channel. Thisdifference in geometry is due to difference in the frequency of unitcells compared to the frequency of the staples 2605 of the staplecavities 2604 a, 2604 b, 2604 c, 2606 a, 2606 b, 2606 c of the staplecartridge 2602. Thus, the attachment features 2622 are positioned onrespective unit cells 2620 at predefined positions that correspond tothe recessed channels 2608, 2610, 2612. As shown in FIG. 26A, and inmore detail in FIGS. 26B-26C, which only illustrates one half (e.g., theleft half) of the adjunct 2600, the respective geometries of theattachment features 2622 are configured to engage respective vertices2608 a, 2610 a, 2610 b, 2612 a of the recessed channels 2608, 2610, 2612that point laterally outward relative to the longitudinal axis L_(A) ofthe staple cartridge 2602. In other embodiments, the geometries of theattachment features can be configured to engage other portions of therecessed channels.

The geometry of the attachment features 2622 can vary laterally and/orlongitudinally relative to the longitudinal axis of the cartridge. Thegeometric variations depend at least upon the frequency of the unitcells 2620 relative to the frequency of the staples 2605 and theshape(s) of the staple cavities 2604 a, 2604 b, 2604 c, 2606 a, 2606 b,2606 c. For example, the attachment features 2622 can vary in at leastone of height (e.g., in the x-direction), width (e.g., in they-direction), length (e.g., in the z-direction), and shape relative toeach other. For example, as shown in FIG. 26B, the height H₁ of a firstattachment feature 2622 a extending from first repeating unit cell 2620a is greater than the height H₂ of a second attachment 2622 b extendingfrom second repeating unit cell 2620 b, and thus the height of the firstand second attachment features 2622 a, 2622 b differ laterally relativeto the longitudinal axis L_(A) of the cartridge 2602. In thisillustrated embodiment, as further shown in FIGS. 26A and 26B, the shapeof each of the first and second attachment features 2622 a, 2622 b alsovaries laterally relative to the longitudinal axis L_(A) of thecartridge 2602. The first attachment feature 2622 a has a cylindricalshaped configuration and the second attachment feature 2622 b has anarcuate configuration. Alternatively, or in addition, the length of twoor more of the attachment features can vary along the longitudinal axisL_(A) of the cartridge 2602. For example, as shown in FIG. 26A, thirdand fourth repeating unit cells 2620 c, 2620 d include third and fourthattachment features 2622 c, 2622 d, respectively, that vary in length(e.g., extending in the z-direction) and shape along the longitudinalaxis L_(A) of the cartridge 2602. In this illustrated embodiment, thethird attachment feature 2622 c has an cylindrical configuration,whereas the fourth attachment feature 2622 d has a triangularconfiguration.

In certain embodiments, lateral variations in the shape and/or height ofthe attachment features can correspond to lateral variations of therecessed channels. For example, while not illustrated, in someembodiments the walls of at least a portion of the recessed channels canextend at an angle relative to the longitudinal axis of the cartridge,and a result one or more of the attachment features can vary in shapeand/or height to correspond thereto. In other embodiments, the length ofthe recessed channels can vary laterally, and one or more of theattachment features can vary in shape and/or height to correspondthereto.

Unit Cell Frequency

Non-strut-based adjuncts can vary in thickness longitudinally (e.g.,along its length, e.g., in the z-direction) and/or laterally (e.g.,along its width, e.g., in the y-direction). As a result, where thefrequency of staples within a longitudinal staple row (e.g., the numberof staples per length of staple row) is different (e.g., greater) thanthe frequency of the repeating unit cells within a correspondinglongitudinal unit cell row (e.g., the number of unit cells per length ofthe cell row), the staple legs of each staple can advance throughdifferent portions of the adjunct with each portion having a relativethickness difference, as illustrated in FIG. 27 .

FIG. 27 illustrates an exemplary embodiment a stapling assembly 2700having a staple cartridge 2702, like staple cartridge 200 in FIGS. 1-2C,and having staples arranged in longitudinal rows (only illustrating fourstaples 2704, 2706, 2708, 2710 of a portion of a first longitudinalstaple row 2712 is being illustrated). An adjunct 2714 is disposed on atop surface 2702 a of the staple cartridge 2702. The adjunct 2714includes interconnected repeating strut-less unit cells, like repeatingunit cells 810 in FIGS. 8A-9C, (only five repeating unit cells 2716 a,2716 b, 2716 c, 2716 d, 2716 e being illustrated) that are arranged inlongitudinal rows (only a portion of a first longitudinal unit cell row2717 being illustrated). As shown, the first longitudinal unit row 2717overlaps with the first longitudinal staple row 2712, and the frequencyof staples 2704, 2706, 2708, 2710 is different than the frequency ofunit cells 2716 a, 2716 b, 2716 c, 2716 d, 2716 e (e.g., non-multiple).As a result, each staple leg 2704 b, 2706 a, 2706 b, 2708 a, 2708 b,2710 a of respective staples 2704, 2706, 2708, 2710 is aligned with, andthus will penetrate through, different respective portions 2718, 2720,2722, 2724, 2726 of the first longitudinal unit cell row 2712, and thusthe adjunct 2714, e.g., when the adjunct 2714 is stapled to tissue.Further, as illustrated in FIG. 27 , due to the structural configurationof the repeating unit cells 2716 a, 2716 b, 2716 c, 2716 d, 2716 e(e.g., generally not square), at least two or more of these differentportions 2718, 2720, 2722, 2724, 2726, 2728 can have a differentrelative thicknesses T₁, T₂, T₃, T₄, T₅ (e.g., thick vs thin), and thusthe thickness of the adjunct 2714 captured within a fired staple willvary among adjacent staples stapled to consistent tissue.

In some embodiments, the difference in relative thickness of the adjunctcan be paired with a corresponding difference in staple leg length. Forexample, when the staple and unit cell frequencies are the same, thelegs of any staples configured to advance through a thicker portion ofthe adjunct can be longer in length than the legs of any staplesconfigured to advance through a thinner portion of the adjunct.Alternatively, or in addition, the difference in relative thickness canbe paired with corresponding differences in anvil pocket depth, or, ifthe staple driver is at the same height, with tissue gap differencesbetween the first staple leg to the second staple if the staple driveris at the same height.

FIG. 28A illustrates an exemplary embodiment of a stapling assembly 2800that is similar to stapling assembly 2700 in FIG. 27 except that thestructural configuration of the adjunct 2801 has been modified such thatthe staple and unit cell frequencies are the same. As a result, thefirst staple leg 2804 a, 2806 a, 2808 a of each staple 2804, 2806, 2808is configured to go through respective portions of the adjunct havingthe same first thickness T₁ and the second staple leg 2804 b, 2806 b,2808 b of each staple 2804, 2806, 2808 is configured to go throughrespective portions of the adjunct 2801 have the same second thicknessT₂. As shown, the first thickness T₁ is greater than the secondthickness T₂, and therefore, to offset the difference in thickness, thefirst leg length L₁ can be greater than the second leg length L₂ foreach staple 2804, 2806, 2808. In this illustrated embodiment, the crown2804 c, 2806 c, 2808 c of each staple 2804, 2806, 2808 has a non-planarconfiguration (e.g., a step-up configuration) to effect the differencein staple leg length. Further, when the staples 2804, 2806, 2808 aredeployed and the adjunct 2801 is stapled to tissue T, each staple willhave two different formed staple heights H₁, H₂, as illustrated in FIG.28B. FIG. 29 illustrates another exemplary embodiment of a staplingassembly 2900 that is similar to stapling assembly 2800 except that thecrown 2904 c, 2906 c, 2908 c of each staple 2904, 2906, 2908 isgenerally planar (e.g., generally straight or linear withinmanufacturing tolerances), and as a result, the formed staple height ofthe first staple will be generally uniform (e.g., nominally identicalwithin manufacturing tolerances).

Strut-Based Adjuncts

As noted above, the adjuncts can include a lattice structure formed ofstrut-based unit cells (e.g., defined by planar interconnected struts).In general, such adjuncts can include a tissue-contacting layer, acartridge-contacting layer, and an internal structure (e.g., bucklingstructure). The internal structure generally includes struts (e.g.,spacer struts) connecting the tissue-contacting layer and thecartridge-contacting layer together in a spaced-apart relation. Thesestruts can be configured to collapse without contacting one anotherwhile the adjunct compresses under stress. As a result, densification ofthe adjunct can be delayed, and thus can occur at a higher strain.

The tissue-contacting layer and cartridge-contacting layer can have avariety of configurations. In some embodiments, at least one of thetissue-contacting layer and the cartridge-contacting layer can include aplurality of struts that define openings. In some embodiments, thetissue-contacting layer and the cartridge-contacting layer are bothgenerally planar (e.g., planar within a manufacturing tolerance). Thetissue-contacting layer and the cartridge-contacting layer can beoriented parallel to one another along a longitudinal axis extendingfrom a first end to a second end of the adjunct, and can further definea vertical axis extending therebetween.

The strut can have various configurations. For example, in someembodiments, a strut can have a generally uniform cross-section (e.g.,uniform within manufacturing tolerances), whereas in other embodimentsthe strut can have a varying cross-section. In some embodiments, theadjunct can have an average strut thickness in a range of about 0.1 mmto 0.5 mm, from about 0.1 mm to 0.4 mm, or from about 0.1 mm to 0.3 mm.

FIGS. 30A-30B illustrate an exemplary strut-based adjunct 3000. Theadjunct 3000 includes a tissue-contacting layer 3002, acartridge-contacting layer 3004, and an internal structure 3006extending therebetween. The internal structure 3006 is configured tocollapse (compress) while the adjunct 3000 is under an applied stress,and therefore cause the adjunct 3000 to compress when stapled to tissue.

While the tissue-contacting layer 3002 and the cartridge-contactinglayer 3004 can have a variety of configurations, in this illustratedembodiment they are both generally planar (e.g., planar withinmanufacturing tolerances). Further, the tissue-contacting layer 3002 andthe cartridge-contacting layer 3004 are parallel to one another along alongitudinal axis (L_(A)) extending from a first end 3000 a to a secondend 3000 b of the adjunct 3000. As shown, the tissue-contacting layer3002 and the cartridge-contacting layer 3004 are inverted images of eachother, with the thickness (T_(C)) of the cartridge-contacting layer 3004being greater than the thickness (T_(T)) of the tissue-contacting layer3002. As such, for sake of simplicity, the following description is withrespect to the tissue-contacting layer 3002. A person skilled in the artwill appreciate, however, that the following discussion is alsoapplicable to the cartridge-contacting layer 3004.

The tissue-contacting layer 3002 has first, second, and thirdlongitudinal struts 3008 a, 3010 a, 3012 a extending along and parallelto the longitudinal axis (L) of the adjunct 3000, in which the secondlongitudinal strut 3010 a is positioned between, but spaced apart from,the first and third longitudinal struts 3008 a, 3012 a. Thetissue-contacting layer 3002 also includes first cross struts 3014 a andsecond cross struts 3016 a. Each of the first cross struts 3014 a isconnected to the first and second longitudinal struts 3008 a, 3010 a.While the first cross struts 3014 a can be oriented in a variety ofdifferent positions, in this illustrated embodiment, the first crossstruts 3014 a are oriented orthogonally relative to the first and secondlongitudinal struts 3008 a, 3010 a. Similarly, each of the second crossstruts 3016 a is connected to the second and third longitudinal struts3010 a, 3012 a. While the second cross struts 3016 a can be oriented ina variety of different positions, in this illustrated embodiment, thesecond cross struts 3016 a are oriented orthogonally relative to thesecond and third longitudinal struts 3010 a, 3012 a. Further, as shown,the first cross struts 3014 a are in alignment with the second crossstruts 3016 a in the y-direction.

Further, the first cross struts 3014 a are longitudinally spaced apartfrom one another at a first distance D₁, and the second cross-struts arelongitudinally spaced apart from one another at a second distance D₂. Asa result, openings 3018 a are created within the tissue-contacting layer3002. While the openings 3018 a can have a variety of sizes and shapes,in this illustrated embodiment, D₁ and D₂ are equal, or substantiallyequal, and therefore, combined with the orientation of the first andsecond cross struts 3014 a, 3016 a, the resulting openings 3018 a are inthe form of rectangles that have generally uniform dimensions (e.g.,nominally identical within manufacturing tolerances).

While the internal structure 3006 can have a variety of configurations,in this illustrated embodiment, the internal structure 3006 includesspacer struts 3020 that extend between the tissue-contacting layer 3002and the cartridge-contacting layer 3004. The spacer struts 3020 includea first set of angled struts 3022 a, 3022 b and a second set of angledstruts 3024 a,3024 b, each of which extend at an angle (e.g., 45degrees) relative to the tissue-contacting and cartridge-contactinglayers 3002, 3004. The first set of angled struts includes first angledstruts 3022 a extending from the first longitudinal strut 3008 a of thetissue-contacting surface 3002 to the second longitudinal strut 3010 bof the cartridge-contacting layer 3004, and second angled struts 3022 bextending from the first longitudinal strut 3008 b to thecartridge-contacting layer 3004 to the second longitudinal strut 3010 aof the tissue-contacting layer 3002. As a result, the first and secondangled struts 3022 a, 3022 b alternate along the length (L) of theadjunct. The second set of alternating angled struts includes thirdangled struts 3024 a and fourth angled struts 3024 b. The third angledstruts 3024 a are similar to the first angled struts 3022 a except thatthe third angled struts 3024 a extend from the second longitudinal strut3010 a of the tissue-contacting layer 3002 to the third longitudinalstrut of 3012 b of the cartridge-contacting layer 3004. The fourthangled struts 3024 b are similar to the second angled struts 3022 bexcept that the fourth angled struts 3024 b extend from the secondlongitudinal strut 3010 b of the cartridge-contacting layer 3004 to thethird longitudinal strut of 3012 a of the tissue-contacting layer 3002.As a result, in this illustrated embodiment, the first and third angledstruts 3022 a, 3024 a extend in the same direction relative to eachother and the second and fourth angled struts 3022 b, 3024 b extend inthe same direction relative to each other.

As further shown in FIG. 30A, openings 3018 b are created within thecartridge-contacting layer 3004 between the first cross struts 3014 band between the second cross-struts 3016 b. Further, the angled struts3022 a, 3022 b, 3024 a, 3024 b substantially overlap with acorresponding opening 3018 b in at least the cartridge-contacting layer3004, and as noted above, the cartridge-contacting layer 3004 has athickness T_(C) that is greater than the thickness T_(T) of thetissue-contacting layer 3002. The openings 3018 b defined in thecartridge-contacting layer 3004 can therefore be configured to receiveat least a portion of the corresponding angled strut as it bends whilethe adjunct 3000 is being compressed under applied stress. This createsadditional space within the internal structure 3006 for buckling, andthus reduces the solid height of the adjunct 3000. As a result, in use,densification of the adjunct 3000 can be delayed such that the adjunct3000 can undergo a more broad range of deformation without reaching itssolid height.

Further, by alternating the angled struts 3022 a, 3022 b, 3024 a, 3024b, a centralized zone 3030 within the internal structure 3006 iscreated. As shown, this centralized zone 3030 extends along the adjunctin a longitudinal direction between the first and second sets of angledstruts 3022 a, 3022 b, 3024 a, 3024 b. As a result, none of the struts3020 within the internal structure 3006 overlap with this centralizedzone 3030, as shown in more detail in FIG. 30B. Stated differently, thiscentralized zone 3030 is designed to be a strut-free space in which noneof the struts cross into prior to or during compression of the adjunct.The presence of this centralized zone 3030 can therefore increase thedensification point of the adjunct 3000 while the adjunct is stapled totissue (e.g., decrease the solid height of the adjunct.). Additionally,the centralized zone can overlap with the cut-line of the adjunct, andtherefore the amount of material along this cut-line can be decreased.This can help facilitate the advancement of a cutting element of astapling device, and therefore make cutting of the adjunct easier.

FIGS. 31A, 32A, 33A, and 34A illustrate various other exemplarystrut-based adjuncts 3100, 3200, 3300, and 3400. Each exemplary adjuncthas a lattice structure formed from repeated interconnected strut-basedunit cells, which are shown in more detail in FIGS. 31B-31D, 32B-32D,33B-33E, and 34B-34E. These adjuncts are structured so as to compresswhen exposed to compressive forces (e.g., applied stress when stapled totissue).

FIG. 31A illustrates another exemplary adjunct 3100 that is in the formof a lattice structure that includes a top portion 3102, a bottomportion 3104, and an internal structure 3106 extending therebetween. Thetop portion 3102 is configured to contact tissue, and therefore formsthe tissue-contacting layer of the adjunct 3100, whereas the bottomportion 3104 is configured to attach to a cartridge, and therefore formsthe cartridge-contacting layer of the adjunct 3100. The internalstructure 3106 can be configured to compress into a deformed state underload, e.g., when stapled to tissue. The lattice is formed of an array ofrepeating unit cells 3110, one of which is shown in more detail in FIGS.31B-31D. As such, for sake of simplicity, the following description iswith respect to the top portion 3102, the bottom portion 3104, and theinternal structure 3106 of one unit cell.

While the top portion 3102 and the bottom portion 3104 can have avariety of configurations, in this illustrated embodiment, the topportion 3102 and bottom portion 3104 are inverted images of each other,and therefore for sake of simplicity, the following description is withrespect to the top portion 3102 of one unit cell 3110. A person skilledin the art will understand, however, that the following discussion isalso applicable to the bottom portion 3104.

As shown in FIGS. 31A-31D, the top portion 3102 includes first andsecond cross struts 3112, 3114, and first and second angled struts 3116,3118 extending therebetween. In this illustrated embodiment, the firstangled strut 3116 extends from a first end of the first cross strut 3112at a first angle and terminates at a mid-portion of the second crossstrut 3114, and the second angled strut 3118 extends from a secondopposite end of the first cross strut 3112 at a second angle andterminates at the mid-portion of the second cross strut 3114. As aresult, the first and second angled struts 3116, 3118 converge andconnect at a central segment 3114 a of the second cross strut 3114. Inother embodiments, the first and second angled struts 3116, 3118 canextend at any other suitable angle.

While the internal structure 3106 can have a variety of configurations,in this illustrated embodiment, the internal structure 3106 includesthree spacer struts 3120 a, 3120 b, 3120 c. As shown in FIGS. 31B-31D,the first and third spacer struts 3120 a, 3120 c each interconnect thefirst cross strut 3112 of the top portion 3102 to the first cross strut3112 of the bottom portion 3104, and the second spacer strut 3120 binterconnects the central segment 3114 a of the second cross strut 3114of the top portion 3102 to the central segment 3114 a of the secondcross strut 3114 of the bottom portion 3104.

FIG. 32A illustrates another exemplary adjunct 3200 that is in the formof a lattice structure that includes a top portion 3202, a bottomportion 3204, and an internal structure 3206 extending therebetween. Thetop portion 3202 is configured to contact tissue, and therefore formsthe tissue-contacting layer of the adjunct 3200, whereas the bottomportion 3204 is configured to attach to a cartridge, and therefore formsthe cartridge-contacting layer of the adjunct 3200. Adjunct 3200 issimilar to adjunct 3100 shown in FIGS. 31A-31D except for thedifferences described below. The lattice is formed of an array ofrepeating unit cells 3201, one of which is shown in more detail in FIGS.32B-32D. As such, for sake of simplicity, the following description iswith respect to the top portion 3202, the bottom portion 3204, and theinternal structure 3206 of one unit cell.

As shown in FIGS. 32B-32D, the top portion 3202 is offset from thebottom portion 3204 in first and second dimensions (X, Z). The topportion 3202 includes two separate sets of interconnected struts 3202 a,3202 b, which are connected to each other via a connecting strut 3203.The bottom portion 3204 includes eight interconnected struts 3204 a, sixof which form a first hexagonal face of the unit cell 3201. The internalstructure 3206 includes two sets of spacer struts 3208 a, 3208 b, 3208c, 3210 a, 3210 b, 3210 c that extend from the top portion 3202 to thebottom portion, thereby forming two additional hexagonal faces of theunit cell 3201, as shown in FIG. 32B.

FIG. 33A illustrates another exemplary adjunct 3300 that is in the formof a lattice structure that includes a top portion 3302, a bottomportion 3304, and an internal structure 3306 extending therebetween. Thetop portion 3302 is configured to contact tissue, and therefore formsthe tissue-contacting layer of the adjunct 3300, whereas the bottomportion 3304 is configured to attach to a cartridge of a surgicalstapler, and therefore forms the cartridge-contacting layer of theadjunct 3300. Adjunct 3300 is similar to adjunct 3100 shown in FIGS.31A-31D except for the differences described below. The lattice isformed of an array of repeating unit cells 3310, one of which is shownin more detail in FIGS. 33B-33E. As such, for sake of simplicity, thefollowing description is with respect to the top portion 3302, thebottom portion 3304, and the internal structure 3306 of one unit cell3310.

While the top portion 3302 and bottom portion 3304 can have a variety ofconfigurations, in this illustrated embodiment, the top portion 3302 andbottom portion 3304 are substantially identical to each other, andtherefore for sake of simplicity, the following description is withrespect to the top portion 3302 of one unit cell 3310. A person skilledin the art will understand, however, that the following discussion isalso applicable to the bottom portion 3304.

As shown in FIGS. 33A-33E, the top portion 3302 includes a first pair ofopposing outside struts 3312 a, 3312 b and a second pair of opposingoutside struts 3312 c, 3312 d. The first and second pairs of outsidestruts 3312 a, 3312 b, 3312 c, 3312 d are connected in such a way inwhich the top portion 3302 is in the form of a parallelogram having fourcorners 3316 a, 3316 b, 3316 c, 3316 d. In this illustrated embodiment,the parallelogram is a square. The top portion 3302 also includes afirst cross strut 3318 that connects the first pair of opposing outsidestruts 3312 a, 3312 b and a second cross strut 3320 that connects thesecond pair of opposing outside struts 3312 c, 3312 d. As shown, thefirst and second cross struts 3318, 3320 intersect at 90 degreesrelative to each other in the middle of the top portion 3302.

While the internal structure 3306 can have a variety of configurations,in this illustrated embodiment, the internal structure 3306 includes afirst side 3322 a, a second adjacent side 3322 b, a third side 3322 cthat is opposite the first side 3322 a, and a fourth side 3322 d that isopposite the second side 3322 b (see FIG. 33D). While each side can havea variety of configurations, in this illustrated embodiment, the firstand third sides 3322 a, 3322 c are substantially identical to each otherand the second and fourth sides 3322 b, 3322 d are substantiallyidentical to each other.

As shown in FIGS. 33B-33E, the first side 3322 a of the internalstructure 3306 includes first and second angled spacer struts 3324 a,3324 b that extend in opposite directions from a central segment 3313 ofthe outside strut 3312 a of the bottom portion 3304 to first and secondcorners 3316 a, 3316 b, respectively, of the top portion 3302.Similarly, the third side 3322 c of the internal structure includes athird angled spacer strut 3326 a and a fourth angled spacer strut 3326 bthat extend in opposite directions from a central segment (obstructed)of the outside strut 3312 b (obstructed) of the bottom portion 3304 tothird and fourth corners 3316 c, 3316 d, respectively, of the topportion 3302.

Further, the second side 3322 b of the internal structure 3306 includesfifth and sixth angled spacer struts 3328 a, 3328 b that extend inopposite directions from a central segment 3315 of the outside strut3312 c of the top portion 3302 to first and fourth corners 3316 a, 3316d, respectively, of the bottom portion 3304. Similarly, the fourth side3322 d of the internal structure 3306 includes a seventh spacer strut3330 a and eighth angled spacer strut (obstructed) that extend inopposite directions from a central segment 3317 of the outside strut3312 d of the top portion 3302 to second and third corners 3316 b (thethird corner of the bottom portion 3304 is obstructed), respectively, ofthe bottom portion 3304.

The internal structure 3306 also includes a first pair of angled spacerstruts 3332 a, 3332 b. The first angled spacer strut 3332 a extends fromthe middle of the top portion 3302 to the central segment 3334 ofoutside strut 3312 c of the bottom portion 3304. Similarly, the secondspacer strut 3332 b extends from the middle of the top portion 3302 tothe central segment (obstructed) of outside strut 3312 d of the bottomportion 3304. As such, the first pair of angled spacer struts 3332 a,3332 b extend in opposite directions from the middle of the top portion3302.

Further, the internal structure 3306 includes a second pair of angledspacer struts 3336 a, 3336 b. The first angled spacer strut 3336 aextends from the middle of the bottom portion 3304 to the centralsegment 3338 of outside strut 3312 b of the top portion 3302. Similarly,the second spacer strut 3336 b extends from the middle of the bottomportion 3304 to the central segment (obstructed) of outside strut 3312 aof the top portion 3302. As such, the second pair of angled spacerstruts 3336 a, 3336 b extend in opposite directions from the middle ofthe bottom portion 3304.

FIG. 34A illustrates another exemplary adjunct 3400 that is in the formof a lattice structure that includes a top portion 3402, a bottomportion 3404, and an internal structure 3406 extending therebetween. Thetop portion 3402 is configured to contact tissue, and therefore formsthe tissue-contacting layer of the adjunct 3400, whereas the bottomportion 3404 is configured to attach to a cartridge a surgical stapler,and therefore forms the cartridge-contacting layer of the adjunct 3400.Adjunct 3400 is similar to adjunct 3100 shown in FIGS. 31A-31D exceptfor the differences described below. The lattice is formed of an arrayof repeating unit cells 3410, one of which is shown in more detail inFIGS. 34B-34E. As such, for sake of simplicity, the followingdescription is with respect to the top portion 3402, the bottom portion3404, and the internal structure 3406 of one unit cell.

While the top portion 3402 and bottom portion 3404 can have a variety ofconfigurations, in this illustrated embodiment, the top portion 3402 andbottom portion 3404 are substantially identical to each other, andtherefore for sake of simplicity, the following description is withrespect to the top portion 3402 of one unit cell 3410. A person skilledin the art will understand, however, that the following discussion isalso applicable to the bottom portion 3404.

As shown in FIGS. 34B-34E, the top portion 3402 includes four crossstruts 3408 a, 3408 b, 3408 c, 3408 d that connect together at themiddle of the top portion 3402. While the four cross struts 3408 a, 3408b, 3408 c, 3408 d can connect together at different angles relative toeach other, in this illustrated embodiment, the four cross struts 3408a, 3408 b, 3408 c, 3408 d connect at 90 degrees relative to each other,and thus form a cross having four outer ends 3411 a, 3411 b, 3411 c,3411 d. The top portion 3402 also includes four struts 3412 a, 3412 b,3412 c, 3412 d that are connected in such a way as to form a squarehaving four corners 3414 a, 3414 b, 3414 c, 3414 d. Each strut 3412 a,3412 b, 3412 c, 3412 d of the square intersects a central segment 3416a, 3416 b, 3416 c, 3416 d (see FIG. 34D) of one of the four struts 3408a, 3408 b, 3408 c, 3408 d of the cross.

While the internal structure 3406 can have a variety of configurations,in this illustrated embodiment, the internal structure 3406 includesfour sets of angled outer struts, in which each set of angled outerstruts includes two angled struts 3418 a, 3418 b, 3420 a, 3420 b, 3422a, 3422 b, 3424 a, 3424 b. The four sets of angled outer struts can havea variety of configurations. As shown, in this illustrated embodiment,the first and second sets of outer struts are mirror images of eachother and the third and fourth sets are mirror images of each other.

As shown in FIG. 34B, the first and second angled struts 3418 a, 3418 bof the first set of angled outer struts each extend in oppositedirections from the first corner 3414 a of the square of the bottomportion 3404 to one of the first and second corners 3411 a, 3411 b,respectively, of the cross of the top portion 3402. Similarly, the firstand second angled struts 3420 a, 3420 b of the second set of angledouter struts each extend in opposite directions from the third corner3414 c (obstructed) of the square of the bottom portion 3404 to one ofremaining corners (e.g., the third and fourth corners 3411 c, 3411 d,respectively) of the cross of the top portion 3402.

As further shown in FIG. 34B, the first and second angled struts 3422 a,3422 b of the third set of angled outer struts each extend in oppositedirections from the second corner 3414 b of the square of the topportion 3404 to one of the second and third corners 3411 b, 3411 c,respectively, of the cross of the bottom portion 3404. Similarly, thefirst and second angled struts 3424 a, 3424 b of the fourth set ofangled outer struts each extend in opposite directions from the fourthcorner 3414 d of the square of the top portion 3404 to one of the firstcorner 3411 a and fourth corner 3411 d (obstructed), respectively, ofthe cross of the bottom portion 3404.

The internal structure 3406 also includes two sets of inner angledstruts, in which each set includes two angled struts 3426 a, 3426 b,3428 a, 3428 b. The two sets of angled inner struts can have a varietyof configurations. As shown in FIG. 34B, the first and second angledstruts 3426 a, 3426 b of the first set of angled inner struts eachextend in opposite directions from the middle of the cross of the topportion 3402 to one of the second corner 3414 b and fourth corner 3414 d(obstructed) of the square of the bottom portion 3404. In thisillustrated embodiment, the first and second angled struts 3428 a, 3428b of the second set of angled inner struts are inverse to the first andsecond angled struts 3426 a, 3426 b. That is, as shown in FIG. 34B, thefirst and second angled struts 3428 a, 3428 b of the second set ofangled inner struts each extend in opposite directions from the middleof the cross of the bottom portion 3404 to one of the first corner 3414a and the third corner 3414 c (obstructed) of the square of the topportion 3402.

As shown in FIGS. 30A-34E, the strut-based configuration of the adjunctsproduce a plurality of openings throughout the adjuncts, therebycreating less of a barrier for cell infiltration as compared tonon-strut-based adjunct configurations. That is, these plurality ofopenings can allow for a more rapid influx of cells into the adjunctwhen the adjunct is stapled to tissue. This increased rate can therebyenhance the rate of tissue ingrowth as compared to other adjuncts.

While the openings in the top portions and bottom portions of theadjuncts shown in FIGS. 31A-34E are regular and symmetrically defined bystruts, in other embodiments, the top portions and bottom portions couldalternatively be planar sheets with regular or irregular openings formedtherein (e.g., “Swiss cheese” style), or non-planar (for example,rippled or wavy) sheets with regular openings or irregular openingsformed therein. These openings of planar and non-planar adjunctconfigurations can also promote cell ingrowth within the adjuncts whenthe adjuncts are stapled to tissue.

In other embodiments, the repeating units of the strut-based adjunctscan have other structural configurations. For example, FIG. 35illustrates an exemplary strut-based unit cell 3500 that can be used toform the adjuncts described herein. The unit cell 3500 includes a topportion 3502, a bottom portion 3504, and an internal structure 3506extending therebetween.

While the top and bottom portions 3502, 3504 can have a variety ofconfigurations, in this illustrated embodiment, the top and bottomportions 3502, 3504 are substantially identical to each other, andtherefore for sake of simplicity, the following description is withrespect to the top portion 3502. A person skilled in the art willunderstand, however, that the following discussion is also applicable tothe bottom portion 3504.

As shown in FIG. 35 , the top portion 3502 includes a first pair ofopposing outside struts 3512 a, 3512 b and a second pair of opposingoutside struts 3514 a, 3514 b. The first and second pairs of outsidestruts 3512 a, 3512 b, 3514 a, 3514 b are connected in such a way inwhich the top portion 3502 is in the form of a parallelogram having fourcorners 3516 a, 3516 b, 3516 c, 3516 d. In this illustrated embodiment,the parallelogram is a square. The top portion 3502 also includes afirst cross strut 3518 that connects the first pair of opposing outsidestruts 3512 a, 3512 b and a second cross strut 3520 that connects thesecond pair of opposing outside struts 3514 a, 3514 b. As shown, thefirst and second cross struts 3518, 3520 intersect at 90 degreesrelative to each other in the middle of the top portion 3502.

While the internal structure 3506 can have a variety of configurations,in this illustrated embodiment, the internal structure 3506 includes afirst side 3522 a, a second adjacent side 3522 b, and a third side 3522c that is opposite the second side 3522 b, and a fourth side 3522 d thatis opposite the first side 3522 a. While each side can have a variety ofconfigurations, in this illustrated embodiment, the first, second,third, fourth sides 3522 a, 3522 b, 3522 c, 3522 d are different. Inthis illustrated embodiment, the fourth side 3522 d does not include anyspacer struts.

As shown in FIG. 35 , the first side 3522 a of the internal structure3506 includes first and second angled spacer struts 3524 a, 3524 b thatextend parallel to each other. The first angled spacer 3524 a strutextends from the first corner 3516 a of the bottom portion 3504 to acenter segment 3513 a of the first outer strut 3512 a of the top portion3502, and the second angled spacer strut extends from a central segment3513 b of the of the first outside strut 3512 a of the bottom portion3504 to the second corner 3516 b of the top portion 3502.

The second side 3522 b of the internal structure 3506 includes third andfourth angled spacer struts 3526 a, 3526 b that extend parallel to eachother. The third angled spacer strut 3526 c extends from the secondcorner 3516 b of the bottom portion 3504 to a central segment 3515 ofthe second outside strut 3514 b of the top portion 3502, and the fourthangled spacer strut 3526 b extends from a central segment (obstructed)of the second outside strut (obstructed) of the bottom portion 3504 tothe third corner 3516 c of the top portion 3502.

Further, the third side 3522 c of the internal structure 3506 includesfifth and sixth angled spacer struts 3528 a, 3528 b that extend parallelto each other. The fifth angled spacer strut 3528 a extends from thefourth corner 3516 d of the bottom portion 3504 to a central segment3517 of the second outside strut 3514 a of the top portion 3502, and thesixth angled spacer strut 3528 b extends from a central segment 3517 ofthe first outside strut 3514 a of the bottom portion 3504 to the firstcorner 3516 a of the top portion 3502.

The internal structure 3506 also includes two sets of internal angledstruts. The first set includes three internal angled struts 3530 a, 3530b, 3530 c that each extend from the middle of the top portion 3502 tocentral segments 3513, 3517, 3519 of outside struts 3512 a, 3514 a, 3512b, respectively, of the bottom portion 3504. As such, in the first set,the first internal angled strut 3530 a and the third internal angledstrut 3530 c extend in opposite directions, and the second internalangled strut 3530 b extends in a different direction relative to thefirst and third internal angled struts 3530 a, 3530 c. The second setincludes three internal angled struts 3532 a, 3532 b, 3532 c that eachextend from the middle of the bottom portion 3504 to central segments3513, 3515, 3519 of outside struts 3512 a, 3514 b, 3512 b, respectively,of the top portion 3502. As such, in the second set, the first internalangled strut 3532 a and the third internal angled strut 3532 c extend inopposite directions, and the second internal angled strut 3532 b extendsin a different direction relative to the first and third internal angledstruts 3532 a, 3532 b.

In other embodiments, the repeating units of the strut-based adjunctscan have other structural configurations. For example, FIG. 36illustrates an exemplary strut-based unit cell 3600 that can be used toform the adjuncts described herein. The unit cell 3600 includes a topportion 3602, a bottom portion 3604, and an internal structure 3606extending therebetween.

While the top and bottom portions 3602, 3604 can have a variety ofconfigurations, in this illustrated embodiment, the top and bottomportions 3602, 3604 are substantially identical to each other, andtherefore for sake of simplicity, the following description is withrespect to the top portion 3602. In an embodiment, the bottom portion3604 is an inverted image of the top portion 3602. A person skilled inthe art will understand, however, that the following discussion is alsoapplicable to the bottom portion 3604.

As shown in FIG. 36 , the top portion 3602 includes a first pair ofcross struts 3612 a, 3612 b and a second pair of cross struts 3612 c,3612 d. The first and second pairs of cross struts 3612 a, 3612 b, 3612c, 3612 d are connected in such a way in which the top portion 3602 isin the form of a sparse tetrahedral having five corners 3616 a, 3616 b,3616 c, 3616 d, 3616 e. The first pair of cross struts 3612 a, 3612 bintersect at intersection 3617 on the top portion. Cross strut 3612 aconnects to cross strut 3612 c at the corner 3616 d, and cross strut3612 b connects to cross strut 3612 d at the corner 3616 c. As shown,cross struts 3612 a, 3612 b intersect at 90 degrees relative to eachother in the middle of the top portion 3602 at intersect 3617.

As shown in FIG. 36 , the internal structure 3606 includes first andsecond angled spacer struts 3620 a, 3620 b that extend parallel to eachother. The first angled spacer strut 3620 a extends from the firstcorner 3616 a of the top portion 3602 to the corner 3616 e of the bottomportion 3604, and the second angled spacer strut 3620 b extends from thethird corner 3616 c of the top portion 3602 to the intersection 3617 ofthe bottom portion 3604. Additionally, the internal structure 3606includes third and fourth angled spacer struts 3622 a, 3622 b thatextend parallel to each other. The third angled spacer strut 3622 aextends from the second corner 3616 b of the top portion 3602 to thecorner 3616 e of the bottom portion 3604, and the fourth angled spacerstrut 3622 b extends from the fourth corner 3616 d of the top portion3602 to the intersection 3617 of the bottom portion 3604. As such, thefirst angled spacer strut 3620 a and the third angled spacer strut 3622a extend in opposite directions, and the second angled spacer strut 3620b and the fourth angled spacer strut 3622 b extend in in oppositedirections.

Outer Layer(s)

In some embodiments, the adjunct can include a lattice structure (e.g.,a first lattice structure or an internal lattice structure) extendingfrom a top surface to a bottom surface, and at least one outer layer,each having different compression ratios (e.g., precompressed height tocompressed height). As a result, the compressive properties of thelattice structure and the at least one outer layer are different, andtherefore can be tailored to carry out different functions (e.g., tissueingrowth, cartridge connection, etc.) while also in combinationeffecting an overall compression profile for the adjunct that isdesirable for varying staple conditions and/or staple heights. Forexample, based on the overall compression profile of the resultingadjunct, the adjunct can be configured, while under an applied stress ina range of about 30 kPa to 90 kPa, to undergo a strain in a range ofabout 0.1 kPa to 0.9 kPa. In other embodiments, the strain can be in therange of about 0.1 to 0.8, of about 0.1 to 0.7, of about 0.1 to 0.6, ofabout 0.2 to 0.8, of about 0.2 to 0.7, of about 0.3 to 0.7, of about 0.3to 0.8, of about 0.3 to 0.9, of about 0.4 to 0.9, of about 0.4 to 0.8,of about 0.4 to 0.7, of about 0.5 to 0.8, or of about 0.5 to 0.9

While the lattice structure and at least one outer layer can have avariety of configurations, in some embodiments, the first latticestructure has a compression ratio that is greater than the compressionratio of the at least one outer layer. For example, in one embodiment,the first lattice structure can be configured, while under an appliedstress, to compress in a range of about 3 mm to 1 mm, and thus, can havea compression ratio of 3, whereas the at least outer layer can beconfigured, while under the same applied stress, to compress in a rangeof about 2 mm to 1 mm, and thus can have a compression ratio of 2.

In certain embodiments, the adjunct can include an outer layer that isin the form of a second lattice structure or absorbable film positionedon at least a portion of the top surface of the first lattice structureand configured to be positioned against tissue. This outer layer can beconfigured to promote tissue ingrowth within the adjunct and/or create asmooth, or substantially smooth, tissue-contacting surface that canslide easily against tissue, and thus, lower the tissue loads (appliedstress) on the adjunct during placement of the stapling device and/orease the attachment requirements between the adjunct and cartridge.Alternatively, or in addition, the adjunct can include an outer layerthat is in the form of a film or a third lattice structure positioned onat least a portion of the bottom surface of the first lattice structureand configured to be positioned against a cartridge. As such, this outerlayer can be configured to attach the adjunct to a cartridge. Forexample, this outer layer can be in the form of an adhesive film and/orinclude one or more attachment features designed to releasably mate withthe staple cartridge. In certain embodiments, the compression ratio ofthe lattice structure is greater than the compression ration of the atleast one outer layer.

FIG. 37A-37B illustrate an exemplary embodiment of an adjunct 3700disposed on a cartridge 3800. The cartridge 3800 is similar to cartridge200 in FIGS. 1-2C, and therefore common features are not described indetail herein. The adjunct 3700 includes an internal lattice structure3702 and two outer layers 3704, 3710, each having a differentcompression ratio relative to each other. The internal lattice structure3702 is generally formed of interconnected repeating unit cells, andwhile the repeating unit cells are omitted from this illustration, anyof the repeating unit cells disclosed herein can be used, e.g.,strut-less based repeating unit cells or strut-based repeating unitcells. Further, the first outer layer 3704 is disposed on the topsurface 3702 a of the internal lattice structure 3702 and is configuredto contact tissue, and the second outer layer 3706 is disposed on thebottom surface 3702 b of the internal lattice structure 3702 and isconfigured to contact the cartridge 3800.

While the first outer layer 3704 can have a variety of configurations,in this illustrated embodiment, the first outer layer 3704 is a latticestructure formed of struts 3710 that are interconnected in such a waythat create hexagonal-shaped openings 3712 that extend through the firstouter layer 3704. These openings 3712 can be configured to promotetissue-ingrowth. A person skilled in the art will appreciate that thestruts can be interconnected in a variety of other ways that wouldeffect openings of different sizes and shapes, and thus, the latticestructure of the first outer layer is not limited to what is illustratedin the figures. Further, the first outer layer 3704 can have a lowercompression ratio, and therefore can be less compressible, compared toat least the internal lattice structure 3702. As a result, this canallow tissue to further penetrate into the openings 3712, and thus theadjunct 3700, when the adjunct 3700 is stapled to tissue, therebyfurther promoting tissue ingrowth (see FIGS. 38A and 38B).

While the second outer layer 3706 can have a variety of configurations,in this illustrated embodiment, the second outer layer 3706 is in theform of a film 3714 having projections 3716 extending outward therefrom.The projections 3716 a, 3716 b, 3716 c are configured to mate with thesurface features 3802, 3804, 3806, of the cartridge 3800, like surfacefeatures 216, 218, 220 of cartridge 200 in FIGS. 1-2C. This matinginteraction, as illustrated in FIGS. 37B and 38A, substantially preventsslideable movement of the adjunct 3700 relative to the cartridge 3800.The shape and size of the projections 3716 a, 3716 b, 3716 c, which canbe triangular or diamond-shaped, are complementary to the shape and sizeof the corresponding surfaces features 3802, 3804, 3806, which can betriangular or diamond-shaped recess channels. In other embodiments, theshape and size of the projections and the surface features can differ.

Alternatively, or in addition, the second outer layer 3706 can includean elongated projection 3730 that is configured to be inserted into thelongitudinal slot 3808 of the cartridge 3800. While the elongatedprojection can have a variety of configurations, in this illustratedembodiment, the elongated projection 3730 has a rectangular shape, Insome embodiments, the elongated projection 3730 can extend along theentire length of the adjunct (e.g., in the z-direction), whereas inother embodiments, the elongated projection 3730 can extend along aportion of the length. In certain embodiments, the elongated projection3730 can be broken up into smaller elongated discrete portions.

In other embodiments, as shown in FIG. 39A, a second outer layer 3900can include four sets of tabs 3902 a, 3902 b, 3904 a, 3904 b, 3906 a,3906 b, 3908 a, 3908 b (3902 b, 3904 b, 3906 b, and 3908 b, beingpartially obstructed in FIG. 39A) that each extend outward and away fromopposing outer sides surfaces 3900 a, 3900 b (FIG. 39B) of the secondouter layer 3900. While the four sets of tabs 3902, 3904, 3906, 3908 canhave a variety of configurations, in this illustrated embodiment, thefour sets of tabs 3902, 3904, 3906, 3908 each have a hooked shapedconfiguration that engage with respective portions of opposing, outerflanges 3910 a, 3910 b, 3910 a, 3910 b, 3914 a, 3914 b, 3914 a, 3914 bof the cartridge 3901. In addition, when the cartridge 3901 includes alongitudinal slot 3918, e.g., a knife slot, the second outer layer 3900can include pin features 3912 that are configured to engage thelongitudinal slot 3918. For example, the pin features 3912 can includesets of two opposing pins (only one set of two opposing tabs 3912 a,3912 b are illustrated in FIGS. 39A-39B) that are spaced intermittentlyalong the longitudinal slot 3918 relative to each other. As shown inmore detail in FIG. 39B, the first pin 3912 a engages a first wall 3918a of the longitudinal slot 3918 and the second pin 3912 b engages asecond, opposing wall 3918 b of the longitudinal slot 3918.

As noted above, in some embodiments, the second outer layer can be anadhesive film. In one exemplary embodiment, as shown in FIG. 40 , anadjunct 4000 is disposed on a top surface 4001 a of a cartridge 4001,like cartridge 200 in FIGS. 1-2C. The adjunct 4000 includes an internalstructure 4002, a first outer layer 4004 disposed on the top surface4002 a of the internal structure 4002, and a second outer layer 4006disposed on the opposing bottom surface 4000 b, which opposes the topsurface 4002 a, of the internal structure 4002. Aside from thedifferences discussed below, the adjunct 4000 can be similar to adjunct3700 in FIGS. 37A-38B and therefore common features are not described indetail herein. As shown, the internal structure 4002 is formed ofinterconnected repeating unit cells 4008, like unit cell 810 in FIGS.8A-9B. Further, the second outer layer 4006 is the form of an adhesivefilm that is attached to the top surface 4001 a of the cartridge 4001.In this illustrated embodiment, the second layer 4006 is an adhesivefilm formed of a pressure sensitive adhesive. Additional details on theadhesive film and other attachment methods can be found in U.S. Pat. No.10,349,939, which is incorporated by reference herein in its entirety.

Staple Pocket Lattices

In some embodiments, the adjunct can also include lattice structuresextending from the second outer layer and configured to be inserted intostaple pockets or recess channels of a staple cartridge. For example, asshown in FIG. 41A, an adjunct 4100 includes an internal latticestructure 4102 extending between two outer layers 4104, 4106. Theinternal lattice structure 4102 is generally formed of interconnectedrepeating unit cells, and while the repeating unit cells are omittedfrom this illustration, any of the repeating unit cells disclosed hereincan be used. Further, each of the two outer layers 4104, 4106 can beformed of either lattice structures or as a film, and therefore, the twoouter layers are each generally illustrated in FIGS. 41A-41C. The firstouter layer 4106 is configured to contact tissue, and, as shown in FIGS.41B-41C, the second outer layer 4104 is configured to contact acartridge 4101. The cartridge 4101 is similar to cartridge 200 in FIGS.1-2C, and therefore common features are not described in detail herein.

As further shown in FIGS. 41A-41C, the adjunct 4100 includes staplepocket lattices 4110 a, 4110 b, 4110 c that extend outward from thesecond outer layer 4104. The staple pocket lattices can function as aseparate compression zone of the adjunct 4100, e.g., the staple pocketlattices 4110 a, 4110 b, 4110 c can have a different compression ratethan that the bulk of the adjunct so as to not substantially add to thesolid height of the overall adjunct. While the staple pocket latticescan have a variety of configurations, in this illustrated embodiment,there are two sets of three longitudinal rows of staple pocket lattices4110 a, 4110 b, 4110 c on opposite sides of the intended cut-line of theadjunct. While the staple pocket lattices can have a variety ofconfigurations, each staple pocket lattice is formed of five U-shapedstruts. The shape and size of the perimeter surrounding the each staplepocket lattice 4110 a, 4110 b, 4110 c can be triangular ordiamond-shaped, and can be complementary to the shape and size of thecorresponding staple pockets 4112 a, 4112 b, 4112 c, which can also betriangular or diamond-shaped. In other embodiments, the shape and sizeof the lattice structures and the staple pockets can differ. As shown inFIGS. 41B-41C, once the adjunct 4100 is disposed on the cartridge 4101,at least a portion of the staples 4114 a, 4114 b, 4114 c within thecartridge 4101 extend through the respective staple pocket lattices 4110a, 4110 b, 4110 c, and therefore captured by the staple crowns when theadjunct is stapled to tissue. Thus, the staple pocket lattices can alsohelp with attachment of the adjunct to the staple cartridge and/or thealignment of the adjunct relative to the staples.

The structural configurations of the unit cells disclosed herein canalso be tailored to effect variable mechanical responses within the sameadjunct, e.g., in the lateral and/or longitudinal directions (e.g., y-and/or z-directions, respectively). For example, in certain embodiments,an adjunct can be formed of at least two or more different latticestructures placed side by side so as to create at least twosubstantially different compressive properties within the same adjunct.

As generally illustrated in FIG. 42A, an adjunct 4200 can have oneinternal lattice structure 4202 and two outside lattice structures 4204,4206, in which each lattice structure 4202, 4204, 4206 definesrespective compression zones C₁, C₂, C₃ of the adjunct 4200. In thisembodiment, the first and second outside lattice structures arestructurally identical, and therefore C₂ and C₃ are the same. As shown,the lattice structures 4202, 4204, 4206 are laterally offset from eachother relative to the longitudinal axis of the adjunct 4200. That is,the first outside lattice structure 4204 is positioned directly adjacentto a first longitudinal side (obstructed) of the internal latticestructure 4202, and the second outside lattice structure 4206 ispositioned directly adjacent to a second, opposing longitudinal side(obstructed) of the internal lattice structure 4202. Since each latticestructure can be formed by any of the repeating unit cells disclosedherein, the three lattice structures 4202, 4204, 4206 are illustratedwithout any unit cells. A person skilled in the art will appreciate thateach lattice structure can be formed of strut-based repeating unit cellsor strut-less based repeating unit cells.

As further shown, the intended cut-line C_(L) of the adjunct 4200 isdefined across the internal lattice structure 4202 and along thelongitudinal axis L_(A) of the adjunct 4200. As such, in thisillustrated embodiment, the internal lattice structure 4202 can beconfigured to be stiffer, and thus exhibit a higher resistance tocompression, compared to the outside lattice structures 4204, 4206.Thus, the resulting adjunct 4200 can have a variable compressionstrength in the lateral direction (e.g., the y-direction) relative tothe cut-line C_(L) of the adjunct 24200. This variable compressionstrength can therefore ease transition of tissue compression at theouter-most staple row 4210 when the adjunct is stapled to tissue, asshown in FIG. 42B.

FIGS. 43A-43B illustrate another embodiment of an adjunct 4300 havingvariable compression strength along a lateral direction (e.g., they-direction) relative to its longitudinal axis L_(A). In thisillustrated embodiment, the adjunct 4300 is formed of three differentlattice structures 4310, 4320, 4330, each being formed of differentrepeating units. More specifically, the first lattice structure 4310 isformed of interconnected first repeating unit cells 4310 a, one of whichis illustrated in FIG. 43A, the second lattice structure 4320 is formedof interconnected second repeating unit cells 4320 a, one of which isillustrated FIG. 43A, and the third lattice structure 4330 is formed ofinterconnected third repeating unit cells 4330 a, one of which isillustrated in FIG. 43A. As described in more detail below, by designingeach lattice structure differently, the resulting adjunct can have avariety of lateral compression responses.

While the repeating unit cells 4310 a, 4320 a, 4330 a can have a varietyof configurations, in this illustrated embodiment, the repeating unitcells 4310 a, 4320 a, 4330 a are all strut-based unit cells. Further,depending on the position of the corresponding lattice structure, therepeating unit cells can be structurally configured such that they aremore or less stiff compared to the repeating unit cells of the otherlattice structures, as described in more detail below.

While the three lattice structures 4310, 4320, 4330 can be positionedrelative to each other in a variety of different configurations, thefirst lattice structure 4310 is the center-most lattice structure of theadjunct in which the intended cut-line C_(L) of the adjunct 4300 extendstherethrough and along the longitudinal axis L_(A). As such, the firstrepeating unit cell 4310 a can have a structural configuration that isless dense, and thus more pliable, compared to the second and thirdrepeating unit cells, e.g., as shown in FIG. 43A. Further, the firstlattice structure 4310 extends along the entire length L of the adjunct4300. The second lattice structure 4320 is divided into two longitudinalportions 4325 a, 4325 b. The first longitudinal portion 4325 a of thesecond lattice structure 4320 is positioned against a first longitudinalside wall L₁ of the first lattice structure 4310 and the secondlongitudinal portion 4325 b of the second lattice structure 4320 ispositioned against a second, opposing longitudinal side wall L₂ of thefirst lattice structure 4310 (see FIG. 43B). Based on their positionrelative to the cut-line C_(L), the second repeating unit cells 4320 acan be configured to be the most dense, and thus most stiff, compared tothe first and third repeating unit cells 4310 a, 4330 a, e.g., as shownin FIG. 43A.

As further shown in FIG. 43A, the third lattice structure is dividedinto two U-shaped portions 4335 a, 4335 b each of which are positionedagainst the outer walls of the respective first and second longitudinalportions 4325 a, 4325 b of the second lattice structure 4320 (only theouter longitudinal walls L₃ and L₄ of each portion 4325 a, 4325 b areillustrated in FIG. 43B). As a result, the third lattice structure 4320defines at least a portion of the outer perimeter of the adjunct 4300.Based on the position of the third lattice structure 4330, the thirdrepeating unit cells can be configured to impart an intermediatedensity, and thus intermediate stiffness, compared to the first andsecond repeating cells 4310 a, 4320 a, as shown in FIG. 43A, which canhelp ease the transition of tissue compression. Further, the structuralconfiguration of the third repeating unit 4330 a can be configured so asto promote tissue in-growth. In certain embodiments, the third latticestructure can also be disposed onto at least a portion of the topsurface of the second lattice structure, which can further enhancetissue in-growth into the adjunct.

In some embodiments, the dimensions (e.g., wall thickness and/or height)of the repeating unit cell can vary among other repeating unit cells.For example, FIGS. 44A-44C illustrate another embodiment of an adjunct4400 having variable compression strength along a lateral direction(e.g., the y-direction) relative to its longitudinal axis (e.g., thez-direction) as a result of varying dimensions of strut-less basedrepeating unit cells. As shown in FIGS. 44A-44B, only one half (e.g.,the left half) of the adjunct 4400 is illustrated on a staple cartridge4401 with three rows of staples 4405 a, 4405 b, 4405 c. While the threerows of staples 4405 a, 4405 b, 4405 c can be generally uniform (e.g.,nominally identical within manufacturing tolerances), in thisillustrated embodiment, the staple height of third row of staples 4405 c(e.g., the outer-most staple row) is greater than the staple height ofthe first and second rows of staples 4405 a, 4405 b. This difference instaple height can be a contributor to the overall compression behaviorof the adjunct. In this illustrated embodiment, the third row of staples4405 c will apply a compressive force to the captured tissue andadjunct, e.g., within the staple's entrapment area, that is less thanthe compressive force applied by the first and second rows of stapes4405 a, 4405 b to respective captured tissue and adjunct, e.g., withinrespective staple entrapment areas. The adjunct 4400 includes two setsof three longitudinal arrays of repeating unit cells. Since both setsare the same, only one set of three arrays 4410, 4412, 4414 and only onerepeating unit cell 4410 a, 4412 a, 4414 a of each of the three arraysare illustrated in FIGS. 44A-44C.

The repeating unit cells 4410 a, 4412 a, 4414 a can have a variety ofconfigurations. In this illustrated embodiment, the repeating unit cells4410 a, 4412 a, 4414 a are similar in overall shape to that of repeatingunit cell 810 in FIG. 9A-9B. However, the wall thickness and heightbetween at least two repeating cells can vary. As shown, the wallthickness W_(T) from the inner-most repeating unit cells 4410 a (e.g.,the first repeating unit cells) to the outer-most repeating unit cell4414 a (e.g., third repeating unit cells) decreases. That is, the wallthickness W_(T1) of inner-most repeating unit cell 4410 a is greaterthan the wall thickness W_(T2) of the intermediate repeating cell 4412a, and the wall thickness W_(T2) of the intermediate repeating cell 4412a is greater than the wall thickness W_(T3) of the outer-most repeatingunit cell 4414. Further, while the height H₁, H₂ of each of theinner-most repeating unit cells 4410 a and intermediate repeating unitcells 4412 a are the same, the height H₁, H₂ is greater than the heightH₃ of the outer-most repeating unit cells 4414 a. In other embodiments,only the wall thickness or the height vary among the arrays, or the wallthickness varies between only two of the three arrays, or the heightvaries among all three arrays.

Alternatively or in addition, in instances where the repeating unitcells are similar in shape to Schwarz-P structures, such as Schwarz-Pstructure 810 in FIGS. 8A-9B, the length of the hollow tubularinterconnections between repeating unit cells of different arrays canvary. For example, as further shown in FIG. 44A, the hollow tubularinterconnection 4416 between the inner-most repeating unit cell 4410 aand the intermediate repeating unit cell 4412 a extend at a first lengthL₁, and the hollow tubular interconnection 4418 between the intermediaterepeating unit cell 4412 a and the outer-most repeating unit cell 4414 aextend at a second length L₂ that is greater than the first length L₁.

The compression behavior of the repeating unit cells 4410, 4410 a of theadjunct 4400 is schematically illustrated in FIGS. 44B-44C as theadjunct 4400 is stapled to tissue. As such, the varying dimensions ofthe repeating unit cells in the lateral direction cause three differentcompression zones with different compressive strengths, the first zonebeing defined by the first longitudinal array 4410 of the firstrepeating units 4410 a having a first compressive strength (e.g., thecapacity of a structure to withstand a compressive force in thex-direction), the second zone being defined by the second longitudinalarray 4412 of the second repeating unit cells 4412 a having a secondcompressive strength, and the third zone being defined by the thirdlongitudinal array 4414 of the third repeating units 4414 a having athird compressive strength. While the compressive strengths among eacharray can vary, in this illustrated embodiment, the first compressivestrength is greater than the second compressive strength, and the secondcompressive strength is greater than the third compressive strength.Thus, the first repeating units 4410 a are stiffer than the secondrepeating until cells 4412 a, and the second repeating unit cells 4412 aare stiffer than the third repeating unit cells 4414 a.

Cartridge Surface Features

In some embodiments, the staple cartridge can include surface features(e.g., staple pocket projections) that can be configured to interactwith the adjunct to help retain the adjunct to the staple cartridgeprior to staple deployment. For example, in certain embodiments, thesurface features can include projections extending outward from the topsurface of the staple cartridge. Alternatively, or in addition, thesurface features can include recessed channels defined within the topsurface of the staple cartridge. As such, the adjuncts described hereincan be designed in a variety of different configurations that aresuitable for interacting with the surface features of a staplecartridge, if present, and thus, effect a releasable attachmentmechanism between the adjunct and the staple cartridge. Alternatively,or in addition, the adjuncts described herein can be designed in avariety of configurations that are suitable for interacting with staplelegs that partially extend outward from their respective cavities withinthe staple cartridge.

FIGS. 45A-45C illustrate an exemplary embodiment of a strut-less basedadjunct 4500 that can be configured to interact with surface features4504 of a staple cartridge 4502. Alternatively, or in addition, theadjunct 4500 can be configured to interact with the legs of the staples4506. 4507, 4508 that are at least partially disposed within the staplecartridge 4502 (see FIGS. 45B-45C). While the staple cartridge 4502 canhave a variety of configurations, in this illustrated embodiment thestaple cartridge 4502 is similar to staple cartridge 200 in FIGS. 1-2Cexcept that the surface features 4504 are U-shaped projections thatextend outward from the top surface 4502 a of the staple cartridge andpositioned about a respective end portion of a staple cavity definedwithin the cartridge 4502. As shown, the staple cavities are arranged infirst and second sets of three longitudinal rows 4510 a, 4510 b, 4510 c,4512 a, 4512 b, 4512 c and positioned on first and second sides of thelongitudinal slot 4514, respectively. Further, for each set, the firstand third longitudinal rows 4510 a, 4510 c, 4512 a, 4512 c are parallelto one another, while the second longitudinal row 4510 b, 4512 b isstaggered with respect thereto.

As further shown in FIGS. 45A-45C, the adjunct 4500 is formed ofinterconnected repeating unit cells 4516 with each unit cell beingstructurally similar to the repeating unit cell 810 in FIGS. 9A-9B.Adjunct 4500 is therefore similar to adjunct 800 in FIGS. 8A-8F exceptthat the repeating unit cells 4515 are rotated 45 degrees about theX-axis with respect to FIG. 8A. In other words, the adjunct 800 isillustrated in a 0-90 configuration, whereas the adjunct 4500 isillustrated in ±45 degrees orientation. As a result, the repeating unitcells 4516 are oriented in a way (e.g., a repeating pattern) that cancoincide with positions of the surface features 4504 and/or staplecavities 4510 a, 4510 b, 4510 c, 4512 a, 4512 b, 4512 c.

As shown in FIG. 45A, the repeating unit cells 4516 are interconnectedto each other and arranged in seven longitudinal rows 4516 a, 4516 b,4516 c, 4516 d, 4516 e, 4516 f, 4516 g each with voids being definedbetween adjacent unit cells (only voids 4518 a, 4518 b, 4518 c, 4520 a,4520 b, 4520 c being illustrated in FIG. 45 and voids 4518 a, 4518 b,4518 c, 4522 a, 4522 b, 4524 a, 4524 b, 4524 c being illustrated inFIGS. 45B-45C). The first three longitudinal rows 4516 a, 4516 b, 4516 care configured to overlap respective staple cavity rows 4510 a, 4510 b,4510 c, the middle-most row 4516 d is configured to overlap with thelongitudinal slot 4514, and the last three longitudinal rows 4516 e,4516 f, 4516 g are configured to overlap respective staple cavity rows4512 a, 4512 b, 4512 c. As a result, as partially illustrated in FIGS.45B-45C, based on the position of the surface features 4504 relative tothe staple cavities, each surface feature 4504 overlaps with and extendsat least partially through a corresponding void. Thus, each void isconfigured to receive and engage at least one surface feature, tothereby retain the adjunct 4500 to the cartridge 4502 prior to stapledeployment. In other embodiments, all or some of the voids can bereplaced with a thinned area of material in which the at least onsurface feature can penetrate into.

Further, as partially illustrated in FIGS. 45B-45C, for each staplecavity row and corresponding row of repeating unit cells, each stapledisposed within a staple cavity (only staples 4506, 4507, 4508 andcorresponding staple cavities rows 4510 a, 4510 b, 4510 c areillustrated in FIG. 45B) extends across a respective repeating unit cellsuch that each staple leg overlaps with a corresponding void positionedon one side of the repeating unit cell. For example, as shown in FIG.45B, with respect to repeating unit cell 4515 a in the first unit cellrow 4516 a and corresponding staple 4508, the first leg 4508 a and thesecond leg 4508 b of the staple 4508 overlap with the first void 4518 aand the second void 4518 b, respectively, which are on opposing sides ofthe repeating unit cell 4515 b in the second unit cell row 4516 b. Asfurther illustrated in FIG. 45C, the staple legs 4507 a, 4507 b extendat least partially through the voids 4522 a, 4522 b, respectively, whenthe adjunct 4500 is positioned on the top surface 4502 a of the staplecartridge 4502. This can further retain the adjunct 4500 to thecartridge 4502 prior to staple deployment. Thus, the repeating unitcells of an adjunct can be configured to be positioned between andengage with the first and second staple legs of a corresponding staple.

FIGS. 46A-46B illustrates another exemplary embodiment of a strut-basedadjunct 4600 that can be configured to interact with surface features ofa staple cartridge 4602. The staple cartridge 4602 is similar to staplecartridge 3901 in FIG. 39A and therefore common features are notdescribed in detailed herein. Each surface feature has a U-shapedconfiguration and is positioned about a respective end portion of eachstaple cavity, and therefore extends along respective longitudinal rowsof staple cavities (only three longitudinal rows of staple cavities 4603a, 4603 b, 4603 c, and therefore three longitudinal rows of surfacefeatures are illustrated in FIGS. 46A-46B).

As shown in more detail in FIG. 46B, the longitudinal row of firstsurface features (only four first surface features 4604 a, 4604 b, 4604c, 4604 d are illustrated) and the longitudinal row of third surfacefeatures (only four third surface features 4608 a, 4608 b, 4608 c, 4608d are illustrated) are laterally aligned with each other in they-direction, and therefore form a set of first lateral rows 4605 a, 4605b, 4605 c, 4605 d, each having respective first and third surfacefeatures. The longitudinal row of second surface features (only foursecond surface features 4606 a, 4606 b, 4606 c, 4606 d are illustrated)are laterally offset with respect to the first and second surfacefeatures in the z-direction, and therefore forms a set of second lateralrows 4607 a, 4607 b, 4607 c, 4607 d, each having a respective secondsurface feature.

Further, aside from the differences described in detail below, theadjunct 4600 is similar to adjunct 3000 in FIGS. 30A-30B. The adjunct4600 includes a tissue-contacting layer 4616, a cartridge-contactinglayer 4618, and an internal structure 4620 extending therebetween.

As shown in FIG. 46 , and in more detail in FIG. 46B, each opening (onlyeight openings 4622 a, 4622 b, 4622 c, 4622 d, 4622 e, 4622 f, 4622 g,4622 h being illustrated) within the cartridge-contacting layer 4618 isconfigured to receive at least one respective surface feature. As aresult, when the adjunct 4600 is positioned on the staple cartridge4602, the respective surface features extend into and engage respectiveopenings within the cartridge-contacting layer 4618. By way of example,as shown in FIG. 46 , the first and third surface features 4604 a, 4608a of the first lateral row 4605 a extend into the first opening 4622 aand engage at least the first cross strut 4624 a, whereas the secondsurface feature 4606 a of the second lateral row 4607 a extends into asecond opening 4622 b and engages at least the first cross strut 4624 aand opposing cross strut 4624 b.

The cross struts (only eight cross struts 4624 a, 4624 b, 4624 c, 4624d, 4624 e, 4624 f, 4624 g are illustrated in FIG. 46B) of thecartridge-contacting layer 4618 can have a variety of configurations.For example, in some embodiments, the width of a cross strut (e.g., inthe z-direction) can be generally uniform (e.g., uniform withinmanufacturing tolerances), whereas in other embodiments, the width of across-strut can be non-uniform. In this illustrated embodiment, thewidth of cross struts 4624 a, 4624 c, 4624 e, 4624 g are uniform,whereas the width of remaining cross struts 4624 b, 4624 d, 4624 f arenon-uniform. A person skilled in the art will appreciate that thestructural configuration of the cross-struts of the cartridge-contactinglayer can depend at least upon the structural configuration of thesurface features. For example, in this illustrated embodiment, at leasta portion of the cross struts include bowing segments to accommodate theU-shaped configuration of the surface features. Depending on theorientation of the U-shaped configuration, some of the bowing segmentshave a convex-configuration, whereas other bowing segments have aconcave-configuration. Further, while the structural configuration ofthe cross struts 4626 a, 4626 b, 4626 c, 4626 d, 4626 e, 4626 f, 4626 gof the tissue-contacting layer 4616 can have a variety ofconfigurations, as shown in FIG. 46A, the cross struts 4626 a, 4626 b,4626 c, 4626 d, 4626 e, 4626 f, 4626 g are structurally similar to thecorresponding cross struts 4624 a, 4624 b, 4624 c, 4624 d, 4624 e, 4624f, 4624 g of the cartridge-contacting layer 4618.

Variable Tissue Gap

In some embodiments, it may be desirable to have a variable tissue gapbetween the adjunct and the anvil to enhance gripping and stabilizationof the tissue during stapling and/or cutting tissue. However, thevariable tissue gap can adversely affect the ability of the adjunct toapply a generally uniform pressure to the stapled tissue. As such, andas described in more detail below, the adjuncts disclosed herein can beconfigured to create a variable tissue gap for tissue manipulation, andwhen stapled to tissue, can further be configured to apply a generallyuniform pressure (e.g., a pressure in a range of about 30 kPa to 90 kPa)to the tissue stapled thereto for a predetermined period of time (e.g.,for at least 3 days). In certain embodiments, the adjuncts can apply apressure of at least about 30 kPa for at least three days. In suchembodiments, after 3 days, the adjuncts can be configured to apply aneffective amount of pressure (e.g., about 30 kPa or less) to the tissuesuch that the tissue can remain sealed through the tissue's healingcycle (e.g., about 28 days). For example, the adjuncts can be configuredto apply a pressure to the stapled tissue, in which the pressuredecreases (e.g., a linear decrease) from about 30 kPa to 0 kPa over apredetermined time period from about 3 days to 28 days, respectively.

In general, the adjunct can include a tissue-contacting surface, acartridge-contacting surface, and an internal structure extendingtherebetween in which the internal structure includes at least twolattice structures each having a different compressive strength. The atleast two lattice structures can vary in structure, shape, orinterconnection laterally along its width and/or longitudinally alongits length to form a variable tissue gap. In some embodiments, the basegeometry of the adjunct can be formed of strut-less based unit cells. Insuch embodiments, the outer geometry of the adjunct can be formed ofstrut-based lattice structures. In other embodiments the base geometrycan be formed of strut-based unit cells.

FIGS. 47A-47B illustrate an exemplary embodiment of a surgical endeffector 4700 having an anvil 4702 and a stapling assembly 4704. Thestapling assembly 4704 includes an adjunct 4706 releasably retained on atop or deck surface 4707 a of a staple cartridge 4707 (e.g., thecartridge surface that faces the anvil). The staple cartridge 4707 issimilar to cartridge 200 in FIGS. 1-2C, and therefore common featuresare not described in detail herein. While not illustrated, the anvil4702 is pivotally coupled to an elongate staple channel, like elongatestaple channel 104 in FIG. 1 , and the stapling assembly 4704 ispositioned within and coupled to elongate staple channel. While theanvil 4702 can have a variety of configurations, as illustrated in FIGS.47A-47B, the anvil includes a cartridge-facing surface having staplepockets 4708 defined therein with a generally planar tissue-compressionsurface 4710 (e.g., planar within manufacturing tolerances) extendingbetween the staple pockets 4708 (e.g., extends in the y-direction). FIG.47A illustrates the surgical end effector 4700, and thus the anvil 4702,in a completely closed position, whereas FIG. 47B illustrates tissue Tbeing clamped between the anvil 4702 and stapling assembly 4704 andbeing stapled to the adjunct 4706 via staples (only two sets of threestaples 4712 a, 4712 b, 4712 c, 4714 a, 4714 b, 4714 c beingillustrated). Prior to deployment, in some embodiments, as illustratedin FIGS. 47A and 47C, the staples can be completely disposed within thestaple cartridge 4707, whereas in other embodiments, some or all thestaples can be partially disposed within the staple cartridge 4707.While the staples 4712 a, 4712 b, 4712 c, 4714 a, 4714 b, 4714 c canhave a variety of configurations, in this illustrated embodiment, thestaples 4712 a, 4712 b, 4712 c, 4714 a, 4714 b, 4714 c have at least agenerally uniform pre-deployed (e.g., unformed) staple height (e.g.,nominally identical within manufacturing tolerances). In someembodiments, the staples 4712 a, 4712 b, 4712 c, 4714 a, 4714 b, 4714 ccan be generally uniform (e.g., nominally identical within manufacturingtolerances).

As shown in FIG. 47A, and in more detail in FIG. 47C, the adjunct 4706has a tissue-contacting surface 4716, a cartridge-contacting surface4718, and an internal structure 4720 extending therebetween. While theinternal structure 4720 can have a variety of configurations, in thisillustrated embodiments, the internal structure includes two latticestructures 4722, 4724 each having a different compressive strength suchthat the adjunct 4706, when in a tissue deployed state, is configured toapply a generally uniform pressure to the stapled tissue for apredetermined period of time. In this illustrated embodiment, the firstlattice structure 4722 is configured to have a first compressivestrength and the second lattice structure 4724 is configured to have asecond compressive strength that is greater than the first compressivestrength.

Each of the first and second lattice structures 4722, 4724 can begenerally formed of unit cells, such as those disclosed herein, e.g.,strut-less based unit cells and/or strut-based unit cells. For example,in certain embodiments, one or more unit cells can include at least onetriply periodic minimal surface structure, such as those disclosedherein. Alternatively, or in addition, one or more unit cells can bedefined by interconnected struts (e.g., planar struts), such as thestrut-based unit cells disclosed herein. In certain embodiments, thefirst and second lattice structures 4722, 4724 can vary in density(e.g., the number of unit cells) and/or shape. As such, aside fromgeneral shape and thickness, the specific structural configuration ofeach of the first and second lattice structures 4722, 4724 is not shown.

The first and second lattice structures 4722, 4724 each extend from atop surface 4722 a, 4724 a to a bottom surface 4722 b, 4724 b. Dependingon the overall structural configuration of the adjunct, at least aportion of the top surface of at least one lattice structure can serveas a tissue-contacting surface of the adjunct, and at least a portion ofthe bottom surface of at least one lattice structure can serve as acartridge-contacting surface of the adjunct. In this illustratedembodiment, the first lattice structure 4722 is positioned on top of thesecond lattice structure 4724 such that the bottom surface 4722 b of thefirst lattice structure 4722 and the top surface 4724 a of the secondlattice structure 4724 are in contact. As such, the top surface 4722 aof the first lattice structure 4722 therefore forms thetissue-contacting surface 4716 and the bottom surface 4724 b of thesecond lattice structure 4724 therefore forms the cartridge-contactingsurface 4718. As a result, the shape of the top surface 4722 a of thefirst lattice structure 4722 can create a tissue gap between the anvil4702 and the stapling assembly 4704 that is independent of the shape ofthe top or deck surface 4707 a of the staple cartridge 4707.

The top and bottom surfaces 4722 a, 4724 a, 4724 a, 4724 b of eachlattice structure 4722, 4724 can have a variety of different shapes. Inthis illustrated embodiment, the top and bottom surfaces 4722 a, 4722 bof the first lattice structure 4722 each have a convex-shapedconfiguration. As such, the top surface 4724 a of the second latticestructure 4724 has a concave-shaped configuration. Further, since thetop or deck surface 4707 a of the staple cartridge 4707 has a generallyplanar configuration (e.g., in the YZ plane), the bottom surface 4724 bof the second lattice structure 4724 also has a generally planarconfiguration (e.g., in the YZ plane). Thus, the resulting overallgeometry of the adjunct 4706 creates a curved tissue-contacting surface4716 relative to the tissue-compression surface 4710 of the anvil 4702,and thus, a variable tissue gap (e.g., two different gap amounts beingillustrated as T_(G1), T_(G2)) between the anvil 4702 and the staplingassembly 4704.

In this illustrated embodiment, due to the concave-shape of the topsurface 4722 a of the first lattice structure 4722, the total thicknessT_(C) (e.g., in the x-direction) at the center of the adjunct 4706(denoted by dotted line 4726, e.g., equidistant from the two opposingterminal lateral-facing edges 4728 a, 4728 b) is greater than the totalthickness T_(P1), T_(P2) (e.g., in the x-direction) at each of theterminal lateral-facing edges 4728 a, 4728 b of the adjunct 4706 (e.g.,the outer longitudinal perimeter of the adjunct 4706 extending in thez-direction). As a result, the overall uncompressed thickness of theadjunct 4706 varies laterally outward along its width relative itscenter (e.g., ±y-direction), and thus varies laterally relative to thelongitudinal axis (e.g., extending in the z-direction) of the adjunct4706. As such, the uncompressed thickness of the adjunct decreases inthe lateral direction while the tissue gap increases. Further, since thetwo terminal lateral-facing edges 4728 a, 4728 b are illustrated asbeing the same thickness, the variation in lateral thickness from thecenter of the adjunct 4706 to each edge is the same. In otherembodiments, the two terminal lateral-facing edges can have differentthickness, and thus, the variation in lateral thickness from the centerof the adjunct to the respective edges would be different.

As further shown, due to the concave-convex surface relationship betweenthe first and second lattice structures 4722, 4724 and their positionand compressive strengths relative to each other, the thickness of eachlattice structure (e.g., in the x-direction) also varies laterallyoutward (e.g., ±y-direction) along their respective lengths (e.g., inthe z-direction) relative to their respective centers, which in thisembodiment is also the center of the adjunct 4706 (denoted by dottedline 4726). As such, in this illustrated embodiment, the first latticestructure 4722 is thicker than the second lattice structure 4724 at thecenter of the adjunct and the second lattice structure 4724 is thickerthan the first lattice structure 4722 at each of the terminallateral-facing edges 4728 a, 4728 b of the adjunct 4706. As a result,the adjunct 4706 is most compressible at its center and leastcompressible at its terminal lateral-facing edges 4728 a, 4728 b, andthus, when in a tissue-deployed state, the adjunct 4706 can compress toa generally uniform thickness T_(compressed) (see FIG. 47B). This allowsthe adjunct 4706 to apply a pressure that is not proportional to itsuncompressed variable thickness. Thus when the adjunct is stapled togenerally uniform tissue T (e.g., tissue having the same orsubstantially the same thickness across the width of the adjunct; in they-direction) with staples 4712 a, 4712 b, 4712 c, 4714 a, 4714 b, 4714c, the adjunct 4706 can apply a generally uniform pressure P to thestapled tissue T (see FIG. 47B).

FIGS. 48A-48B illustrate another exemplary embodiment of a surgical endeffector 4800 having an anvil 4802 and a stapling assembly 4804. Thestapling assembly 4804 includes an adjunct 4806 releasably retained on atop or deck surface 4807 a of a staple cartridge 4807 (e.g., thecartridge surface that faces the anvil). Aside from the differencesdescribed below, the anvil 4802 is similar to anvil 4702 in FIGS.47A-47B, and the staple cartridge 4807 is similar to cartridge 200 inFIGS. 1-2C, except that the top or deck surface 4807 a is curved, andtherefore common features are not described in detail herein. FIG. 48Aillustrates the surgical end effector 4800, and thus the anvil 4802, ina completely closed position, whereas FIG. 48B illustrates tissue Tbeing clamped between the anvil 4802 and stapling assembly 4802 andbeing stapled to the adjunct 4806 via staples (only two sets of threestaples 4812 a, 4812 b, 4812 c, 4814 a, 4814 b, 4814 c beingillustrated). Prior to deployment, in some embodiments, as illustratedin FIGS. 48A and 48C, the staples can be completely disposed within thestaple cartridge 4807, whereas in other embodiments, some or all thestaples can be partially disposed within the staple cartridge 4807.While the two sets of staples 4812 a, 4812 b, 4812 c, 4814 a, 4814 b,4814 c can have a variety of configurations, in this illustratedembodiment, the two sets of staples are same, and thus for each set, thefirst staples 4812 a, 4814 a (e.g., inner-most row of staples) have afirst height, the second staples 4812 b, 4814 b (e.g., intermediate rowof staples) have a second height that is greater than the first height,and the third staples 4812 c, 4814 c (e.g., the outer-most row ofstaples) have a third height that is greater than the second height.

As shown in FIG. 48A, and in more detail in FIG. 48C, the adjunct 4806has a tissue-contacting surface 4816, a cartridge-contacting surface4818, and an internal structure 4820 extending therebetween. While theinternal structure 4820 can have a variety of configurations, in thisillustrated embodiments, the internal structure 4820 includes twolattice structures 4822, 4824 each having a different compressivestrength such that the adjunct 4806, when in a tissue deployed state, isconfigured to apply a generally uniform pressure to the stapled tissuefor a predetermined period of time. In this illustrated embodiment, thefirst lattice structure 4822 is configured to have a first compressivestrength and the second lattice structure 4824 is configured to have asecond compressive strength that is greater than the first compressivestrength.

Each of the first and second lattice structures 4822, 4824 can begenerally formed of unit cells, such as those disclosed herein, e.g.,strut-less based unit cells and/or strut-based unit cells. For example,in certain embodiments, one or more unit cells can include at least onetriply periodic minimal surface structure, such as those disclosedherein. Alternatively, or in addition, one or more unit cells can bedefined by interconnected struts (e.g., planar struts), such as thestrut-based unit cells disclosed herein. As such, aside from generalshape and thickness, the specific structural configuration of each ofthe first and second lattice structures 4822, 4824 is not shown.

The first and second lattice structures 4822, 4824 each extend from atop surface 4822 a, 4824 a to a bottom surface 4822 b, 4824 b. Dependingon the overall structural configuration of the adjunct, at least aportion of the top surface of at least one lattice structure can serveas a tissue-contacting surface of the adjunct, and at least a portion ofthe bottom surface of at least one lattice structure can serve as acartridge-contacting surface of the adjunct. In this illustratedembodiment, the first lattice structure 4822 is narrower in width (e.g.,in the y-direction) compared to the second lattice structure andtherefore is positioned only on top of a center region 4823 of thesecond lattice structure 4824. As such, the entire bottom surface 4822 bof the first lattice structure 4822 contacts only a portion of the topsurface 4824 a of the second lattice structure 4824, e.g., the topsurface 4823 a of only the center region 4823. As a result, the topsurface 4822 a of the first lattice structure 4822 and the two exposedportions 4825 a, 4825 b of the top surface 4824 a of the second latticestructure 4824 form the tissue-contacting surface 4816 and the bottomsurface 4824 b of the second lattice structure 4824 forms thecartridge-contacting surface 4818.

The top and bottom surfaces 4822 a, 4824 a, 4824 a, 4824 b of eachlattice structure 4822, 4824 can have a variety of different shapes. Aperson skilled in the art will appreciate that the shape of the top andbottom surfaces can depend at least upon the top or deck surface of thestaple cartridge to which the adjunct is to be releasably retainedthereto. In this illustrated embodiment, the top and bottom surfaces4822 a, 4822 b of the first lattice structure 4822 each have aconvex-shaped configuration. As such, the top surface 4823 a of thecenter region 4823 of the second lattice structure 4824 has aconvex-shaped configuration, while the two exposed portions 4825 a, 4825b of the top surface 4824 a of the second lattice structure 4824 eachhave a generally planar configuration (e.g., extending in they-direction). Further, since the top or deck surface 4807 a of thestaple cartridge 4807 has a convex-shaped configuration, the bottomsurface 4824 b of the second lattice structure 4824 has a concave-shapedconfiguration.

In this illustrated embodiment, due to the structural interconnectionbetween the first and second lattice structures 4822, 4824 and theresulting shape of the tissue-contacting surface 4816, the totalthickness T_(C) (e.g., in the x-direction) at the center of the adjunct4806 (denoted by dotted line 4826, e.g., equidistant from the outer-mostterminal lateral-facing edges 4828 a, 4828 b) is less than the totalthickness T_(P1), T_(P2) (e.g., in the x-direction) at each of the outermost terminal lateral-facing edges 4828 a, 4828 b of the adjunct (e.g.,the outer longitudinal perimeter of the adjunct 4806 extending in thez-direction). As a result, the overall uncompressed thickness of theadjunct 4806 varies laterally outward along its width relative itscenter (e.g., ±y-direction). Thus, the overall uncompressed thickness ofthe adjunct varies laterally relative to the longitudinal axis (e.g.,extending in the z-direction) of the adjunct 4806.

As further shown, due to at least the structural relationship betweenthe first and second lattice structures 4822, 4824 and their compressivestrengths relative to each other in combination with thecurved-configuration of the top surface 4807 a of the staple cartridge4807, the thickness of each lattice (e.g., in the x-direction) alsovaries laterally outward along their respective lengths relative totheir respective centers (e.g., ±y-direction), which in this embodiment,is also the center of the adjunct 4806 (denoted by dotted line 4826). Assuch, in this illustrated embodiment, the first lattice structure 4822is thicker than the second lattice structure 4824 at the center of theadjunct 4806. As a result, the adjunct 4806 is most compressible at itscenter and least compressible at its outer-most terminal lateral-facingedges 4828 a, 4828 b. This allows the adjunct 4806 to apply a generallyuniform pressure despite its variations in its compressed thickness.Thus, when the adjunct is stapled to substantially uniform tissue T(e.g., tissue having the same or substantially the same thickness (e.g.,in the x-direction) across the width of the adjunct (e.g., in they-direction) with staples 4812 a, 4812 b, 4812 c, 4814 a, 4814 b, 4814c, the adjunct 4806 compresses to a non-uniform compressed thicknesswhile still applying a generally uniform pressure P to the stapledtissue T (see FIG. 48B). As further shown, in this illustratedembodiment, only the second lattice 4824 overlaps with the outer-mostrow of staples 4812 c, 4814 c.

In other embodiments, the second lattice structure can be narrower inwidth than the first lattice structure. For example, as shown in FIG. 49, the adjunct 4900 includes first and second lattice structures 4906,4908 having a semi-circular concentric configuration, in which the firstlattice structure 4906 envelops the second lattice structure 4908. As aresult, the top surface 4906 a of the first lattice structure 4906 formsthe tissue-contacting surface 4902 of the adjunct 4900 and the bottomsurfaces 4906 b, 4908 b of the first and second lattice structures 4906,4908 form the cartridge-contacting surface 4904 of adjunct 4900.

As noted above, the adjunct can have two lattice structures that vary instructure, shape, or interconnection longitudinally along the length ofthe adjunct (e.g., in the z-direction). For example, as illustrated inFIGS. 50A-50B, the adjunct 5002 includes two lattice structures 5004,5006 that each vary in structure and shape relative to each other andalong the length of the adjunct (e.g., extending along the longitudinalaxis L_(A); in the z-direction).

FIGS. 50A-50B illustrate an exemplary embodiment of a surgical endeffector 5000 that is similar to surgical end effector 5000 except forthe adjunct 5002, which has a variable compression strength along itslength that extends along the longitudinal axis L_(A) (e.g., in thez-direction). As shown in FIG. 50A, and in more detail in FIG. 50C, theadjunct 5002 is positioned on a top or deck surface 5003 a of a staplecartridge 5003. The staple cartridge 5003 is similar to staple cartridge4707 in FIGS. 47A-47C with staples 4712 a, 4712 b, 4712 c, 4714 a, 4714b, 4714 c disposed therein, and therefore common features are notdescribed herein.

The adjunct 5002 has a tissue-contacting surface 5008, acartridge-contacting surface 5010, and an internal structure 5012extending therebetween. While the internal structure 5012 can have avariety of configurations, the first and second lattice structures 5004,5006 each have a different compressive strength such that the adjunct5002, when in a tissue deployed state, is configured to apply agenerally uniform pressure (e.g., a pressure in a range of 30 kPa to 90kPa) to the tissue stapled thereto for a predetermined period of time(e.g., for at least 3 days). In this illustrated embodiment, the firstlattice structure 5004 is configured to have a first compressivestrength and the second lattice structure 5006 is configured to have asecond compressive strength that is greater than the first compressivestrength. Thus, the second lattice structure 5004 is stiffer compared tothe first lattice structure 5006. In other embodiments, the firstlattice structure can be stiffer than the second lattice structure.

Each of the first and second lattice structures 5004, 5006 can begenerally formed of unit cells, such as those disclosed herein, e.g.,strut-less based unit cells and/or strut-based unit cells. For example,in certain embodiments, one or more unit cells can include at least onetriply periodic minimal surface structure, such as those disclosedherein. Alternatively, or in addition, one or more unit cells can bedefined by interconnected struts (e.g., planar struts), such as thestrut-based unit cells disclosed herein. In certain embodiments, thefirst and second lattice structures 5004, 5006 can vary in density(e.g., the number of unit cells) and/or shape. As such, aside fromgeneral shape and thickness, the specific structural configuration ofeach of the first and second lattice structures 5004, 5006 is not shown.

The first and second lattice structures 5004, 5006 each extend from atop surface 5004 a, 5006 a to a bottom surface 5004 b, 5006 b. Dependingon the overall structural configuration of the adjunct, at least aportion of the top surface of at least one lattice structure can serveas a tissue-contacting surface of the adjunct, and at least a portion ofthe bottom surface of at least one lattice structure can serve as acartridge-contacting surface of the adjunct. In this illustratedembodiment, the first lattice structure 5004 is positioned on top of thesecond lattice structure 5006 such that the bottom surface 5004 b of thefirst lattice structure 5004 and the top surface 5006 a of the secondlattice structure 5006 are in contact. As such, the top surface 5004 aof the first lattice structure 5004 forms the tissue-contacting surface5008 and the bottom surface 5006 b of the second lattice structure 5006forms the cartridge-contacting surface 5010.

While the first and second lattice structures 5004, 5006 can have avariety of configurations, each lattice structure has an uncompressedthickness (e.g., in the x-direction) that varies along the length of theadjunct (e.g., extending in the z-direction). As shown, the top surface5004 a of the first lattice structure 5004 inclines from the proximalend 5002 a to the distal end 5002 b of the adjunct 5002. Further, sincethe top or deck surface 5003 a of the staple cartridge 5003 has agenerally planar configuration (e.g., in the XZ plane), the bottomsurface 5006 b of the second lattice structure 5006 also has a generallyplanar configuration (e.g., in the XZ plane). As a result, a variabletissue gap (e.g., two different gap amounts being illustrated as T_(G1),T_(G2)) is created between the anvil 5001 and the adjunct 5002 that isindependent of the shape of the top or deck surface 5003 a of the staplecartridge 5003.

When the adjunct is stapled to tissue, as illustrated in FIG. 50B, thevariations in uncompressed thicknesses of each lattice structure alongthe length of the adjunct, in combination with the first and secondcompression strengths and variable tissue gap, can allow the adjunct toapply a generally uniform pressure P to the stapled T (see FIG. 50B).

Consistent Tissue Gap

In some embodiments, it may be desirable to have a consistent tissue gapbetween the adjunct and the anvil to enhance gripping and stabilizationof the tissue during stapling and/or cutting tissue. However, theconsistent tissue gap can adversely affect the ability of the adjunct toapply a generally uniform pressure to the stapled tissue. As such, andas described in more detail below, the adjuncts disclosed herein can beconfigured to create a consistent tissue gap for tissue manipulation,and when stapled to tissue, can further be configured to apply agenerally uniform pressure (e.g., a pressure in a range of about 30 kPato 90 kPa) to the tissue stapled thereto for a predetermined period oftime (e.g., for at least 3 days). In certain embodiments, the adjunctscan apply a pressure of at least about 30 kPa for at least three days.In such embodiments, after 3 days, the adjuncts can be configured toapply an effective amount of pressure (e.g., a linear decrease inpressure, e.g., about 30 kPa or less) to the tissue such that the tissuecan remain sealed through the tissue's healing cycle (e.g., about 28days). For example, the adjuncts can be configured to apply a pressureto the stapled tissue, in which the pressure decreases (e.g., a lineardecrease) from about 30 kPa to 0 kPa over a predetermined time periodfrom about 3 days to 28 days, respectively.

In some embodiments, the adjunct can be designed with atissue-contacting surface in which at least a portion is generallyplanar (e.g., in the y-direction) and an opposing cartridge-contactingsurface that is non-planar (e.g., along the width of the adjunct, e.g.,in the y-direction). The non-planar surface of the cartridge-contactingsurface can vary proportionally along and relative to, e.g., a curved ora stepped top or deck surface of a staple cartridge (e.g., the cartridgesurface that faces the anvil) or a stepped tissue-compression surface ofan anvil.

In general, the adjunct can include a tissue-contacting surface, acartridge-contacting surface, and an internal structure extendingtherebetween. In some embodiments, the adjunct can be formed of at leasttwo lattice structures, with a first lattice structure having anon-planar bottom surface that defines at least a portion of thecartridge-contacting surface, and a second lattice structure (e.g.,primary lattice structure) having a top surface with at least a portionthat is generally planar and that defines at least a portion of thetissue-contacting surface. In other embodiments, the internal structurecan be formed of a single lattice structure formed of repeating unitcells that vary in shape and/or dimension in the lateral directionrelative to the longitudinal axis of the adjunct. As a result, theadjunct can have an overall geometry that creates a tissue-contactingsurface having planar and non-planar surfaces and a non-planarcartridge-contacting surface that is configured to mate to a curved orstepped top or deck surface of the staple cartridge (e.g., the cartridgesurface that faces the anvil). Thus, a generally consistent tissue gapcan be created independent of the shape of the top or deck surface ofthe staple cartridge.

In some embodiments, the dimensions (e.g., wall thickness and/or height)of the repeating unit cells can be varied such that, when the adjunct isstapled to tissue, the adjunct can apply a generally uniform pressure(e.g., a pressure in a range of 30 kPa to 90 kPa) to the stapled tissuefor a predetermined period of time (e.g., for at least three days). Forexample, the repeating unit cells of one longitudinal row can varyrelative to the repeating unit cells of an adjacent longitudinal row.Thus, an adjunct can be designed in such a way that, prior to stapledeployment, the adjunct can create a consistent tissue gap with theanvil, and when in a tissue-deployed state, can apply a generallyuniform pressure (e.g., a pressure in a range of 30 kPa to 90 kPa) tothe stapled tissue for a predetermined period of time (e.g., for atleast three days).

FIG. 51A illustrates an exemplary embodiment of a surgical end effector5100 having an anvil 5102 and a stapling assembly 5104. The staplingassembly 5104 includes an adjunct 5106 releasably retained on a top ordeck surface 5108 a of a staple cartridge 5108 (e.g., the cartridgesurface that faces the anvil). Aside from the differences describedbelow. the staple cartridge 5108 is similar to cartridge 4807 in FIGS.48A-48C, and therefore common features are not described in detailherein. While not illustrated, the anvil 5102 is pivotally coupled to anelongate staple channel, like elongate staple channel 104 in FIG. 1 ,and the stapling assembly 5104 is positioned within and coupled toelongate staple channel. While the anvil 5102 can have a variety ofconfigurations, in the embodiment shown in FIG. 51A, the anvil 5102includes a cartridge-facing surface having staple pockets 5110 definedtherein with a generally planar tissue-compression surface 5112extending between the staple pockets 5110. FIG. 51A illustrates thesurgical end effector 5100, and thus the anvil 5102, in a completelyclosed position, without tissue positioned between the anvil 5102 andthe adjunct 5106, and staples disposed within the staple cartridge 5108(only two sets of three staples 5114 a, 5114 b, 5114 c, 5116 a, 5116 b,5116 c being illustrated). Prior to deployment, in some embodiments, asillustrated in FIG. 51A, the staples 5114 a, 5114 b, 5114 c, 5116 a,5116 b, 5116 c can be partially disposed within the staple cartridge5108, whereas in other embodiments, some or all the staples can becompletely disposed within the staple cartridge 5108. While the staples5114 a, 5114 a, 5114 c, 5116 a, 5116 b, 5116 c can have a variety ofconfigurations, in this illustrated embodiment, the staples 5114 a, 5114a, 5114 c, 5116 a, 5116 b, 5116 c have at least a generally uniformpre-deployed (e.g., unformed) staple height (e.g., nominally identicalwithin manufacturing tolerances). In some embodiments, the staples 5114a, 5114 a, 5114 c, 5116 a, 5116 b, 5116 c can be generally uniform(e.g., nominally identical within manufacturing tolerances).

As shown in FIG. 51A, and in more detail in FIG. 51B, the adjunct 5106has a tissue-contacting surface 5118, a cartridge-contacting surface5120, and an internal structure 5122 extending therebetween. While theinternal structure 5122 can have a variety of configurations, in thisillustrated embodiments, the internal structure 5122 includes twodifferent lattice structures 5124, 5126. The first and second latticestructure 5124, 5126 each extend from a top surface 5124 a, 5126 a to abottom surface 5124 b, 5126 b.

The first lattice structure 5124 can be generally formed of struts, likestruts 5228 a, 5228 b, 5228 c, 5228 d, 5230 a, 5230 b, 5230 c, 5230 d inFIGS. 52A-52B, or unit cells, such as those disclosed herein, e.g.,strut-less based unit cells and/or strut-based unit cells. As such,aside from general overall shape and thickness, the specific structuralconfiguration of the first lattice structure 5124 is not shown.

The first lattice structure 5124 extends between the second lattice 5126structure and the top or deck surface 5108 a of the staple cartridge5108. As shown, the uncompressed thickness of the first latticestructure 5124 varies laterally relative to the longitudinal axis L_(A)(e.g., L_(A) extending in the z-direction) of the adjunct 5106. Theselateral variations can be proportionate along the curved top or decksurface 5108 a of the staple cartridge 5108 such that the portion of thecartridge-contacting surface 5120 of the adjunct 5106 that is formed bythe bottom surface 5124 b of the first lattice structure 5124 iscomplementary in shape to the curved top or deck surface 5108 a of thestaple cartridge 5108 (e.g., a concave-shaped configuration). As aresult, the thickness changes of the first lattice structure 5124 canconform to the changes in the top or deck surface 5108 a. Further, thiscauses the compression ratio of the first lattice structure 5124 to alsovary in the lateral direction, which in this illustrated embodiment,increases due to the lateral increase in uncompressed thickness suchthat the compression behavior of the adjunct 5106 is predominantlydriven by the compression properties of the second lattice structure5126.

The second lattice structure 5126 is formed of interconnected repeatingunit cells that are arranged in two sets of three longitudinal arrays,with the first set positioned on one side of the intended cut line ofthe adjunct and the second set positioned on the second of the intendedcut line of the adjunct. For sake of simplicity, only three unit cellsfrom each set 5132 a, 5132 b, 5132 c, 5134 a, 5134 b, 5134 c, are beingillustrated. While the repeating unit cells can have a variety ofconfigurations, in this illustrated embodiment, all of the repeatingunit cells have generally uniform dimensions (e.g., nominally identicalwithin manufacturing tolerances) and are similar to repeating unit cell810 in FIGS. 9A-9B, and therefore common features are not described indetail herein. As such, the second lattice structure is similar toadjunct 800 in FIGS. 8A-8F, and therefore common features are notdescribed herein.

As shown, at least a portion of the top surface 5126 a is generallyplanar, and thus includes generally planar surfaces 5127 (e.g., each inthe y-direction) with non-planar surfaces 5129 extending therebetween.The top surface 5126 a defines the tissue-contacting surface 5118 of theadjunct 5106, and thus the tissue-contacting surface 5118 is formed ofplanar surfaces 5127 and non-planar surfaces 5129. Since the generallyplanar surfaces 5127 and non-planar surfaces 5129 of the top surface,and thus of the tissue-contacting surface 5118, alternate along thewidth of the second lattice structure 5126 (extending in they-direction), a consistent tissue gap (e.g., alternating betweengenerally uniform tissue gaps and variable tissue gaps) is createdbetween the anvil 5102 and the adjunct 5106. In this illustratedembodiment, each generally uniform tissue gap T_(G) occurs between thetissue-compression surface 5112 of the anvil 5102 and the generallyplanar surfaces 5127 of the tissue-contacting surface 5118. The variabletissue gaps (only two variable gaps being illustrated as T_(G1), T_(G2))occur between the tissue-compression surface 5112 of the anvil 5102 andthe non-planar surfaces 5129 of the tissue-contacting surface 5118,which extend between the adjacent unit cells of the second latticestructure 5126. A person skilled in the art will appreciate that thelength of the generally uniform and variable tissue gaps (extending inthe x-direction) can depend at least upon the structural configurationof the tissue-contacting surface, and thus the structural configurationof the second lattice structure.

While the height between the repeating unit cells 5132 a, 5132 b, 5132c, 5134 a, 5134 b, 5134 c, is generally uniform, the wall thickness canvary, and therefore result in different compression ratios. In thisillustrated embodiment, the two sets of three longitudinal arrays arethe same, and therefore for each set, the wall thickness W_(T) from thefirst repeating unit cell 5132 a, 5134 a (e.g., the inner-most repeatingunit cells) to the third repeating unit cell 5132 c, 5134 c (e.g.,outer-most repeating unit cells) decreases similarly. As such, only theone set of the three longitudinal arrays are illustrated in FIG. 51B.The wall thickness W_(T1) of first repeating unit cell 5132 a (notillustrated) is greater than the wall thickness W_(T2) of the secondrepeating unit cell 5132 b (e.g., intermediate repeating unit cells),and the wall thickness W_(T2) of the second repeating cell 5132 b isgreater than the wall thickness W_(T3) of the third repeating unit cell5132 c, 5134 c. As a result, the compression ratio from the firstrepeating unit cell 5132 a, 5134 a to the third repeating unit cell 5132c, 5134 c increases, and thus the first repeating unit cell 5132 a, 5134a will compress the least (e.g., most stiff) and the third repeatingunit cell 5132 c, 5134 c will compress the most (e.g., least stiff).That is, the first compression ratio of the first repeating unit cell5132 a, 5134 a is less than each of the second and third compressionratios of the second and third repeating unit cells 5132 b, 5134 b, 5132c, 5134 c, respectively, and the second compression ratio is less thanthe third compression ratio. These compression ratios, in combinationwith the laterally varying compression ratio of the first latticestructure 5124, will therefore generate a varying overall compressionratio of the adjunct 5106 such that, when the adjunct is stapled totissue with generally uniform staples 5114 a, 5114 b, 5114 c, 5116 a,5116 b, 5116 c (e.g., nominally identical within manufacturingtolerances), the adjunct 5106 is configured to apply a generally uniformpressure to the stapled tissue for a predetermined time period.

In certain embodiments, the first lattice structure can be configured insuch a way that it does not overlap with staple rows when the adjunct isreleasably retained on a staple cartridge. As such, the first latticestructure will not be captured, or will be minimally captured, by thestaples during deployment. As a result, the first lattice structure willnot contribute, or will minimally contribute, to the solid height of theadjunct when in a tissue-deployed state. Thus, densification of theadjunct can be delayed.

FIG. 52A illustrates another exemplary embodiment of a surgical endeffector 5200 having an anvil 5202 and a stapling assembly 5204. Thestapling assembly 5204 includes an adjunct 5206 releasably retained on atop or deck surface 5208 a of a staple cartridge 5208 (e.g., thecartridge surface that faces the anvil). Aside from the differencesdescribed below, the anvil 5202 and staple cartridge 5208 are similar toanvil 5102 and staple cartridge 5208 in FIGS. 52A-52B, and thereforecommon features are not described in detail herein.

The adjunct 5204 is similar to adjunct 5104 in FIGS. 51A-51B except thatthe first lattice structure 5224 is formed of two sets of fourlongitudinal rows of spaced apart vertical planar struts (e.g., in thex-direction) that extend between the second lattice 5226 structure andthe top or deck surface 5208 a of the staple cartridge 5208. As shown,the first set is positioned on one side of the intended cut line C_(L)of the adjunct 5206 and the second set is positioned on the second sizeof the intended cut line C_(L) of the adjunct 5206. For sake ofsimplicity, only four struts from each set 5228 a, 5228 b, 5228 c, 5228d, 5230 a, 5230 b, 5230 c, 5230 d are illustrated. While the two sets ofstruts can have a variety of configurations, in this illustratedembodiment, the two sets of struts are the same, and thus for each set,the first struts 5228 a, 5230 a (e.g., inner-most row of struts) have afirst height, the second struts 5228 b, 5228 b (e.g., inner-mostintermediate row of struts) have a second height that is greater thanthe first height, the third struts 5228 c, 5230 c (e.g., outer-mostintermediate row of struts) have a third height that is greater than thesecond height, and the fourth struts 5228 d, 5230 d (e.g., theouter-most row of struts) have a fourth height that is greater than thesecond height. As such, the uncompressed thickness (e.g., along thewidth of the adjunct; in the y-direction) of the first lattice structure5224 varies laterally relative to the longitudinal axis L_(A) (e.g.,L_(A) extending in the z-direction) of the adjunct 5206. These lateralvariations can be proportionate along the curved top or deck surface5208 a of the staple cartridge 5208 such that the portion of thecartridge-contacting surface 5220 of the adjunct 5206 that is formed bythe bottom surface 5224 b of the first lattice structure 5224 iscomplementary in shape to the curved top or deck surface 5208 a of thestaple cartridge 5208 (e.g., a concave-shaped configuration). Thus, thethickness changes of the first lattice structure 5224 can conform to thechanges in the top or deck surface 5208 a.

As further shown in FIG. 52A, in an effort to minimize the impact thefirst lattice structure 5224 can have on the densification of theadjunct 5206, the first lattice structure 5224 can be designed in such away that it does not overlap with the staples 5214 a, 5214 a, 5214 c,5216 a, 5216 b, 5216 c. For example, in this illustrated embodiment,none of the struts 5228 a, 5228 b, 5228 c, 5228 d, 5230 a, 5230 b, 5230c, 5230 d, overlap with any of the staples 5214 a, 5214 b, 5214 c, 5216a, 5216 b, 5216 c, and thus, the first lattice structure 5224 will notbe captured by the staples during deployment. As a result, when theadjunct 5206 is stapled to tissue, the applied pressure to the stapledtissue by the adjunct 5206 can be completely, or substantiallycompletely, dependent on the compressive properties of the secondlattice structure 5226.

In some embodiments, the wall thickness and height of each repeatingunit cell can vary among other repeating unit cells. For example, FIG.53 illustrates another exemplary embodiment of an adjunct 5300releasably retained on a top or deck surface 5302 a of a staplecartridge 5302 (e.g., the cartridge surface that faces the anvil). Asidefrom the differences described below, the staple cartridge 5302 issimilar to staple cartridge 5108 in FIGS. 51A-51B, and therefore commonfeatures are not described in detail herein. As shown in FIG. 53 , onlyone half (e.g., the right half) of the adjunct 5300 is illustrated onthe staple cartridge 5302 with three rows of staples 5304, 5306, 5308partially disposed therein, in which the inner-most staple row 5304 hasthe smallest staple height and the outer-most staple row 5308 has thelargest staple height. As noted above, the difference in staple heightcan be a contributor to the overall compression behavior of the adjunctwhen the adjunct is stapled to tissue.

While the adjunct 5300 can have a variety of configurations, the adjunct5300 is formed of interconnected repeating unit cells that are arrangedin two sets of three longitudinal arrays, with the first set positionedon one side of the intended cut line C_(L) of the adjunct 5300 and thesecond set (not shown) positioned on the second of the intended cut lineC_(L) of the adjunct 5300. Since both sets are the same, only onerepeating unit cell 5310, 5312, 5314 of one set of the threelongitudinal arrays are illustrated in FIG. 53 .

The repeating unit cells 5310, 5312, 5314 can have a variety ofconfigurations. In this illustrated embodiment, the repeating unit cells5310, 5312, 5314 are similar in overall shape except the wall thicknessand height vary among the three repeating unit cells 5310, 5312, 5314.As shown, each repeating cell has a varying height (e.g., in theX-direction) from their respective outer-most top surface 5310 a, 5312a, 5314 a, which are laterally offset and aligned relative to each otherin the y-direction, to their respective outer-most bottom surface 5310b, 5312 b, 5314 b, and thus for simplicity, the minimum and maximumheights H_(1A), H_(1B) for the repeating unit cell 5310, the minimum andmaximum height H_(2A), H_(2B) for the repeating unit cell 5312, and theminimum and maximum heights H_(3A), H_(3B) for the repeating unit cell5314 is illustrated.

As shown, a portion of the top surface 5300 a of the adjunct 5300 isgenerally planar and thus, includes generally planar surfaces 5316(e.g., each in the y-direction) with non-planar surfaces 5318 extendingtherebetween. The top surface 5300 a defines the tissue-contactingsurface 5320 of the adjunct 5300, and thus the tissue-contacting surface5320 is formed of planar surfaces 5316 and non-planar surfaces 5318.Since the generally planar surfaces 5316 and non-planar surfaces 5318 ofthe top surface 5300 a, and thus of the tissue-contacting surface 5320,alternate along the width of the adjunct 5300 (extending in they-direction), a consistent tissue gap (e.g., alternating betweengenerally uniform tissue gaps and variable tissue gaps) is createdbetween the anvil, like anvil 5102 in FIG. 51 , and the adjunct 5300. Inthis illustrated embodiment, each generally uniform tissue gap occursbetween the tissue-compression surface, like tissue-compression surface5112 of anvil 5102 in FIG. 51 , and the generally planar surfaces 5316of the tissue-contacting surface 5320. The variable tissue gaps occurbetween the tissue-compression surface, like tissue-compression surface5112 of anvil 5102 in FIG. 51 , and the non-planar surfaces 5318 of thetissue-contacting surface 5320, which extend between the adjacent unitcells of the adjunct 5300. A person skilled in the art will appreciatethat the length of the generally uniform and variable tissue gaps(extending in the x-direction) can depend at least upon the structuralconfiguration of the tissue-contacting surface, and thus the structuralconfiguration of the adjunct.

Further, the wall thickness and the height between at least tworepeating cells can vary, and therefore result in different compressionratios. In this illustrated embodiment, the wall thickness W_(T) and Hfrom the first repeating unit cell 5310 (e.g., the inner-most repeatingunit cells) to the third repeating unit cell 5314 (e.g., outer-mostrepeating unit cells) increases. That is, the wall thickness W_(T1) andheight H₁ of first repeating unit cell 5310 is less than the wallthickness W_(T2) and height H₂ of the second repeating unit cell 5312(e.g., intermediate repeating unit cells), and the wall thickness W_(T2)and height H₂ of the second repeating cell 5312 is less than the wallthickness W_(T3) and height H₃ of the third repeating unit cell 5314. Asa result, the compression ratio from the first repeating unit cell 5310to the third repeating unit cell 5314 decreases. That is, the firstcompression ratio of the first repeating unit cell 5310 is greater thaneach of the second and third compression ratios of the second and thirdrepeating unit cells 5312, 5314, respectively, and the secondcompression ratio is greater than the third compression ratio. Thesecompression ratios will therefore generate a varying overall compressionratio of the adjunct 5300 such that, when the adjunct is stapled totissue with staples 5304, 5306, 5308 with varying staple lengths (e.g.,the inner-most staples 5304 having the least staple height and theouter-most staples 5308 having the greatest height), the adjunct 5300 isconfigured to apply a generally uniform pressure to the stapled tissuefor a predetermined time period.

As noted above, the adjunct can include a combination of strut-lessbased unit cells and strut-based unit cells and/or spacer struts. Forexample, FIG. 54 illustrates an exemplary embodiment of an adjunct 5400releasably retained on a top or deck surface 5402 a of a staplecartridge 5402 (e.g., the cartridge surface that faces the anvil). Asidefrom the differences described below, the staple cartridge 5402 issimilar to staple cartridge 200 in FIGS. 1-2C, and therefore commonfeatures are not described in detail herein. As shown in FIG. 54 , onlyone half (e.g., the left half) of the adjunct 5400 is illustrated on thestaple cartridge 5402 with three longitudinal rows 5303 a, 5303 b, 5303c of substantially uniform staples 5404 a, 5404 b, 5404 c disposedtherein.

While the adjunct 5400 can have a variety of configurations, as shownthe adjunct has an internal lattice structure 5406 formed of two sets oftwo longitudinal arrays of repeating strut-less based unit cells, withthe first set positioned on one side of the intended cut line C_(L) ofthe adjunct 5400 and the second set (not shown) positioned on the secondof the intended cut line C_(L) of the adjunct 5400. Since both sets arethe same, only one repeating unit cell 5408, 5410 of one set of the twolongitudinal arrays is illustrated in FIG. 54 . Further, the adjunct5400 includes first and second outer lattice structures that arestructurally similar and are positioned on opposite sides of theinternal lattice structure (only the first outer lattice structure 5412being illustrated). While only the first outer lattice structure 5412and the first and second repeating unit cells 5408, 5410 of the adjunct5400 are illustrated, a person skilled in the art will appreciate thatthe following discussion is also applicable to the second latticestructure and the second set of longitudinal arrays of repeating cells.

The first and second repeating unit cells 5408, 5410 can have a varietyof configurations. In this illustrated embodiment, the repeating unitcells 5408, 5410 are generally uniform (e.g., nominally identical withinmanufacturing tolerances) and are structurally similar to repeating unitcell 810 in FIGS. 9A-9B, and therefore common features are not describedin detail herein. As shown, the first and second repeating unit cells5408, 5410 are oriented similar to the repeating unit cells 4516 inFIGS. 45A-45C, and therefore the internal lattice structure 5406 canhave a structurally similar configuration to adjunct 4500 in FIGS.45A-45C. As a result, the repeating unit cells 5408, 5410 are orientedin a way (e.g., a repeating pattern) that can coincide with thepositions of the staples in one or more of the staple rows that theinternal lattice structure 5406 overlaps. As further shown, the firstouter lattice structure 5412 includes strut-based unit cells (only twounit cells 5414 a, 5414 b are fully illustrated). While the strut-basedunit cells can have a variety of configurations, the first strut-basedunit cell 5414 a has a triangular configuration and the secondstrut-based unit cell 5414 b has an inverted triangular configuration.As further shown, a portion of the second strut-based unit cell 5414 bcrosses over the first strut-based unit cell 5414 a.

As shown, the lattice structures 5406, 5412 are adjacent to andlaterally offset from each other relative to the longitudinal axis L_(A)of the adjunct 5400 (e.g., L_(A) extending in the z-direction). That is,the first outer lattice structure 5412 is positioned directly adjacentto a first longitudinal side 5406 a of the internal lattice structure5406. Further, the internal lattice structure 5406 overlaps with thefirst and second staple rows 5403 a, 5303 b (e.g., inner-most staple rowand intermediate staple row), and thus the first and second staples 5404a, 5404 b, respectively, whereas the first outer lattice structure 5412overlaps with the third staple row 5404 c (e.g., the outer-most staplerow), and thus the third staples 5404 c. In this illustrated embodiment,the first longitudinal array of the first repeating unit cells 5408 andthe second longitudinal array of the second repeating unit cells 5410are staggered relative to each other, and thus oriented in a way (e.g.,a repeating pattern) that coincides with the positions of the first andsecond staples 5404 a, 5404 b, respectively.

This alignment of the lattice structures 5406, 5412 relative to thefirst, second, and third staples 5404 a, 5404 b, 5404 c, in combinationwith the different structural configurations of the lattice structures5406, 5412, can result in at least two different stress-strain curveswhen the adjunct is stapled to tissue. Given the orientation of thefirst and second repeating unit cells relative to the first and secondstaples, the resulting stress-strain curve of the adjunct at the firstand second staples can be the same, or substantially the same. Thecompressive behavior of adjunct 5300 at each of the first, second, andthird staples 5404 a, 5404 b, 5404 c is schematically illustrated inFIG. 55 , in which S1 represents the stress-strain curve of the adjunctat the first staples 5404 a, S2 represents the stress-strain curve ofthe adjunct at the second staples 5404 b, and S3 represents thestress-strain curve at the third staples 5404 c. In this schematic, thestress-strain curves S1, S2 at the first and second staples areillustrated as the same curve. A person skilled in the art willappreciate that the stress-strain curves at each staple can vary.

Adjunct Systems

In general, the adjunct systems described herein can include at leasttwo different adjuncts, in which each adjunct, while under a respectiveapplied stress in a range of about 30 kPa to 90 kPa, is configured toundergo a respective strain in a respective range of strains. In someembodiments, at least two respective ranges of strain can at leastpartially overlap, whereas in other embodiments, at least two respectiveranges do not overlap. In addition, or alternatively, the combination ofthe respective ranges of strain can result in a combined range from atleast 0.1 to 0.9. In other embodiments, the combined range can be ofabout 0.1 to 0.8, of about 0.1 to 0.7, of about 0.1 to 0.6, of about 0.1to 0.5, of about 0.1 to 0.4, of about 01. to 0.3, of about 0.2 to 0.8,of about 0.2 to 0.7, of about 0.3 to 0.7, of about 0.3 to 0.8, of about0.3 to 0.9, of about 0.4 to 0.9, of about 0.4 to 0.8, of about 0.4 to0.7, of about 0.5 to 0.8, or of about 0.5 to 0.9. While the adjunctsystems can include at least two different adjuncts, for sake ofsimplicity, the following description is with respect to an adjunctsystem having only first and second adjuncts. A person skilled in theart will understand, however, that the following discussion is alsoapplicable to additional adjuncts of an adjunct system.

In some embodiments, the adjunct system can include first and secondadjuncts in which, the first adjunct, while under an applied stress in arange of about 30 kPa to 90 kPa, undergoes a strain in a first range,and the second adjunct, while under an applied stress in a range ofabout 30 kPa to 90 kPa, undergoes a strain in a second range. Thestress-strain response of each adjunct depends at least upon thestructural configurations and compositional makeup of each adjunct. Assuch, the first and second adjuncts can be tailored to effect a desiredstrain response under an applied stress and/or a range of appliedstresses. For example, in some embodiments, the first adjunct can beconfigured such that, while under an applied stress in a range of about60 kPa to 90 kPa, the first adjunct undergoes a strain in a first rangeof about 0.2 to 0.5, whereas the second adjunct can be configured suchthat, while under an applied stress in a range of about 40 kPa to 70kPa, the second adjunct undergoes a strain in a second range of about0.3 to 0.7. In another embodiment, the first adjunct can be configuredsuch that, while under an applied stress in a range of about 30 kPa to90 kPa, the first adjunct undergoes a strain in a first range of about0.1 to 0.7, whereas the second adjunct can be configured such that,while under an applied stress in a range of about 30 kPa to 90 kPa, thesecond adjunct undergoes a strain in a second range of about 0.3 to 0.9.In another embodiment, the first adjunct can be configured such that,while under an applied stress in a range of about 30 kPa to 90 kPa, thefirst adjunct undergoes a strain in a first range of about 0.2 to 0.6,whereas the second adjunct can be configured such that, while under anapplied stress in a range of about 30 kPa to 90 kPa, the second adjunctundergoes a strain in a second range of about 0.4 to 0.8. In anotherembodiment, the first adjunct can be configured such that, while underan applied stress in a range of about 40 kPa to 80 kPa, the firstadjunct undergoes a strain in a first range of about 0.1 to 0.7, whereasthe second adjunct can be configured such that, while under an appliedstress in a range of about 30 kPa to 90 kPa, the second adjunctundergoes a strain in a second range of about 0.2 to 0.8.

The first and second adjuncts can have a variety of structuralconfigurations. For example, the first adjunct can have a configurationsimilar to any one of the exemplary adjuncts described herein and thesecond adjunct can have a different configuration than the first adjunctand similar to another one of the exemplary adjuncts described herein.In some embodiments, the first adjunct can be a non-strut based adjunctand the second adjunct can be another non-strut based adjunct or astrut-based adjunct described herein. In other embodiments, the firstadjunct can be a strut-based adjunct and the second adjunct can beanother strut-based adjunct or a non-strut based adjunct.

In some embodiments, the first adjunct has a first internal structureformed of a first plurality of repeating interconnected unit cells, andthe second adjunct has a second internal structure formed of a secondplurality of repeating interconnected unit cells. In certainembodiments, the first plurality of repeating interconnected unit cellscan be formed of a first material and the second plurality of repeatinginterconnected unit cells can be formed of a second material that isdifferent than the first material. The first and second materials can beany of the materials described herein and in more detail below. Inaddition, or alternatively, each unit of the first plurality ofrepeating interconnected unit cells has a first geometry and each unitof the second plurality of repeating interconnected unit cells has asecond geometry that is different than the first geometry.

In some embodiments, each unit cell of at least one of the firstplurality of repeating interconnected unit cells and the secondplurality of repeating interconnected unit cells is a triply periodicminimal surface structure (e.g., a Schwarz-P structure). In oneembodiment, each unit cell of the first plurality of repeatinginterconnected unit cells is a first triply periodic minimal surfacestructure, and each unit cell of the second plurality of repeatinginterconnected unit cells is a second triply periodic minimal surfacestructure that is different than the first triply periodic minimalsurface structure. For example, the first and second triply periodicminimal surface structures can differ in geometry, e.g., shape, size(e.g., height, wall thickness, and the like), or a combination thereof.

In some embodiments, each unit cell of the first plurality of repeatinginterconnected unit cells can include a first top portion formed from afirst plurality of struts defining a first plurality of openingstherebetween, a first bottom portion formed from a second plurality ofstruts defining a second plurality of openings therebetween, and firstspacer struts that interconnect the first top portion and the firstbottom portion. In such embodiments, each unit cell of the secondplurality of repeating interconnected unit cells can be a Schwarz-Pstructure. In other embodiments, each unit cell of the second pluralityof repeating interconnected unit cells can include a second top portionformed from a third plurality of struts defining a third plurality ofopenings therebetween, a second bottom portion formed from a fourthplurality of struts defining a fourth plurality of openingstherebetween, and second spacer struts that interconnect the second topportion and the second bottom portion.

Materials

The adjuncts described herein can be formed of one or more polymers,such as bioabsorbable polymer(s), non-bioabsorbable polymer(s),bioresorbable polymer(s), or any combination thereof. For claritypurposes only, the use of “polymers” herein can be understood toencompass one or more polymers, including one or more macromers.Non-limiting examples of suitable polymers include polylactide (PLA),polycaprolactone (PCL), polyglycolide (PGA), polydioxanone (PDO),polytrimethylene carbonate (PTMC), polyethylene glycol (PEG),polyethylene diglycolate (PEDG), polypropylene fumarate (PPF),poly(ethoxyethylene diglycolate), a poly(ether ester) (PEE), apoly(amino acid), poly(epoxycarbonate), poly(2-oxypropylene carbonate),poly(diol citrates), polymethacrylate anhydrides, andpoly(N-isopropylacrylamide), a copolymer of any thereof, or anycombination thereof. Non-limiting examples of suitable copolymersinclude random copolymers such as PLGA-PCL, block copolymers such aspoly(lactide-co-glycolide) (PLGA), triblock copolymers such asPLGA-PCL-PLGA or PLGA-PEG-PLGA, or any combination thereof. Additionalnon-limiting examples of suitable polymers are disclosed in, forexample, U.S. Pat. Nos. 9,770,241, 9,873,790, 10,085,745, and10,149,753; and in U.S. Patent Pub. No. 2017/0355815, each of which isincorporated by reference herein in its entirety.

In some embodiments, the polymers can be formed from a resin. Ingeneral, the resins described herein can be suitable for use in additivemanufacturing techniques such as bottom-up and top-downstereolithography, (b) produce adjuncts that are bioresorbable, and/or(c) produce adjuncts that are flexible or elastic (e.g., attemperature(s) of about 25° C., of about 37° C., and/or any temperaturetherebetween).

In some embodiments, the polymer can be formed from a lightpolymerizable resin that includes oligomer prepolymer(s). The oligomerprepolymer(s) can be linear or branched (e.g., “star” oligomers such astri-arm oligomers). Non-limiting examples of suitable end groups forsuch oligomer prepolymers include acrylate, methacrylate, fumarate,vinyl carbonate, methyl ester, ethyl ester, etc. Non-limiting examplesof suitable constituents of exemplary resins that can be used to formpolymers, and consequently, the adjuncts provided herein, are listed inTable 2 below. Constituents in each column of Table 2 can be combinedwith constituents of the other columns in any combination.

TABLE 2 Exemplary Resin Compositions Backbone Reactive End OligomerPhoto- Chemistry Group Architecture Plasticizer Diluent initiator PLGAMethacrylate Linear HO-PCL-OH Mono-vinyl Irgacure ® ether 2959 PCLAcrylate Star HO-PLGA-PCL-PLGA-OH DEGMA Irgacure ® (branching) TPOPLGA-PCL-PLGA Vinyl Hyperbranched Vinyl acetate ITX CarbonatePLGA-PEG-PLGA Unsaturated Pendant n-butyl Irgacure ® Fatty acidmethacrylate 819 methyl ester PLGA-PCL Dendritic Triacetine PDO-PCL-PDONMP PGA-PTMC-PGA DMSO PLC-PGA NMP PGA-PLC-PGA DMSO Divinyl Adipate PLGA= poly(lactide-co-glycolide); PEG = poly(ethylene glycol); PCL =polycaprolactone; PLC = poly(lactide-co-caprolactone); PDO =Polydioxanone; PTMC = Poly(trimethylene carbonate); DEGMA = Di(ethyleneglycol) methyl ether methacrylate; TPO = diphenyl(2,4,6-trimethylbenzoyl) phosphine oxide; ITX = isopropylthioxanthone;NMP = N-methyl pyrrolidone; DMSO = dimethyl sulfoxide.

While various types of resins can be used to form the polymers, in someembodiments, the polymers are formed from a resin that is based on abioresorbable polyester oligomer (e.g., a methacrylate terminatedoligomer with a bioresorbable polyester linkage). For example, thebioresorbable polyester oligomer can be present in an amount from about5% to 90%, from 5% to 80%, from about 10% to 90%, or from about 10% to80% by weight of the resin. Unlike conventional resins (e.g.,polycaprolactone dimethacylate based resins and poly(D,L-lactide)dimethacrylate based resins), this resin can form an adjunct havingrubber-like elastic behavior at physiological temperatures, short-termretention of mechanical properties (e.g., 1 month or less), and/orlong-term full resorption (e.g., over a time period of approximately 4-6months).

In some embodiments, the oligomer can include a linear oligomer.Alternatively, or in addition, the oligomer can include a branchedoligomer (e.g., a star oligomer, such as a tri-arm oligomer).

In some embodiments, the bioresorbable polyester oligomers describedherein are bioresorbable oligomers with methacrylate end-groups. Sucholigomers typically include biodegradable ester linkages betweenconstituents such as caprolactone, lactide, glycolide trimethylenecarbonate, dioxanone and propylene fumarate monomers in an ABA block,BAB block, CBC block, BCB block, AB random composition, BC randomcomposition, homopolymer, or any combination thereof, where:A=poly(lactide) (PLA), poly(glycolide) (PGA), poly(lactide-co-glycolide)(PLGA), or polypropylene fumarate (PPF), B=polycaprolactone (PCL),poly(lactide-co-caprolactone) (PLACL), poly(glycolide-co-caprolactone)(PGACL), poly(trimethylene carbonate) (PTMC), orpoly(caprolactone-co-lactide) (PCLLA), and C=polydioxanone (PDO). Thecopolymers can have a molecular weight (Mn) from about 2 kilodaltons to6 kilodaltons, from about 2 kilodaltons to 10 kilodaltons, from about 2kilodaltons to 15 kilodaltons, from about 2 kilodaltons to 20kilodaltons, from about 2 kilodaltons to 50 kilodaltons, from about 5kilodaltons to 6 kilodaltons, from about 5 kilodaltons to 10kilodaltons, from about 5 kilodaltons to 15 kilodaltons, from about 5kilodaltons to 20 kilodaltons, from about 5 kilodaltons to 50kilodaltons, from about 10 kilodaltons to 15 kilodaltons, from about 10kilodaltons to 20 kilodaltons, or from about 10 kilodaltons to 50kilodaltons, in either linear or star structure. Monomers used toproduce such oligomers may optionally introduce branches, such as toenhance elasticity, an example being gamma-methyl-epsilon caprolactoneand gamma-ethyl-epsilon-caprolactone.

In some embodiments, lactides can include L-Lactides, D-Lactide, ormixtures thereof (e.g., D,L-Lactides). For example, in some embodimentswith PLA blocks, L-Lactide can be used for better regularity and highercrystallinity.

In some embodiments, the oligomer can include an ABA block, a BAB block,a CBC block, or a BCB block in linear and/or branched (e.g., star ortri-arm) form.

In some embodiments, A can be: (i) poly(lactide); (ii) poly(glycolide);(iii) poly(lactide-co-glycolide) containing lactide and glycolide in amolar ratio of 90:10 to 55:45 lactide:glycolide (e.g., a lactide richratio), 45:55 to 10:90 lactide:glycolide (e.g., a glycolide rich ratio),or 50:50 lactide:glycolide; or any combination thereof. In suchembodiments, the oligomer can be in linear and/or branched (e.g., staror tri-arm) form. In some embodiments, a D,L-Lactide mixture can be usedfor making the PLGA random copolymer.

In some embodiments, B can be: (i) polycaprolactone; (ii)polytrimethylene carbonate; (iii) poly(caprolactone-co-lactide)containing caprolactone and lactide in a molar ratio of 95:5 to 5:95caprolactone:lactide; or any combination thereof.

In some embodiments, A (PLA, PGA, PLGA, PPF, or any combination thereof)can have a molecular weight (Mn) from about 1 kilodaltons to 4kilodaltons, from about 1 kilodaltons to 6 kilodaltons, from about 1kilodaltons to 10 kilodaltons, from about 2 kilodaltons to 4kilodaltons, from about 2 kilodaltons to 6 kilodaltons, or from about 2kilodaltons to 10 kilodaltons; and B (PCL, PLACL, PGACL, PTMC, PCLLA, orany combination thereof) can have a molecular weight (Mn) from about 1kilodaltons to 4 kilodaltons, from about 1 kilodaltons to 6 kilodaltons,from about 1 kilodaltons to 10 kilodaltons, from about 1 kilodaltons to50 kilodaltons, from about 1.6 kilodaltons to 4 kilodaltons, from about1.6 kilodaltons to 6 kilodaltons, from about 1.6 kilodaltons to 10kilodaltons, or from about 1.6 kilodaltons to 50 kilodaltons.

The resin can also include additional constituents, such as additionalcross-linking agent(s), non-reactive diluent(s), photoinitiator(s),reactive diluent(s), filler(s), or any combination thereof.

In some embodiments, the resin can include an additional cross-linkingagent. For example, the additional cross-linking agent can be present inan amount from about 1% to 5%, from about 1% to 10%, from about 2% to5%, or from about 2% to 10% by weight of the resin. Any suitableadditional cross-linking agents can be used, including bioabsorbablecross-linking agents, non-absorbable cross-linking agents, or anycombination thereof. Non-limiting examples of suitable bioabsorbablecross-linking agents include divinyl adipate (DVA),poly(caprolactone)trimethacrylate (PCLDMA, e.g., at a molecular weightMW of about 950 to 2400 daltons), etc. Non-limiting examples of suitablenon-absorbable cross-linking agents include trimethylolpropanetrimethacrylate (TMPTMA), poly(propylene glycol) dimethacrylate(PPGDMA), poly(ethylene glycol) dimethacrylate (PEGDMA), etc.

In some embodiments, the resin can include a non-reactive diluent. Forexample, the non-reactive diluent can be present in an amount from about1% to 70%, from about 1% to 50%, from about 5% to 70%, or from about 5%to 50% by weight of the resin. Non-limiting examples of non-reactivediluents include dimethylformamide, dimethylacetamide, N-methylpyrrolidone (NMP), dimethyl sulfoxide, cyclic carbonate (e.g., propylenecarbonate), diethyl adipate, methyl ether ketone, ethyl alcohol,acetone, or any combination thereof.

In some embodiments, the resin can include a photoinitiator. Forexample, the photoinitiator can be present in an amount from about 0.1%to 4%, from about 0.1% to 2%, from about 0.2% to 4%, or from about 0.2%to 2% by weight of the resin. Photoinitiators included in the resin canbe any suitable photoinitiator. Non-limiting examples of suitablephotoinitiators include type I and type II photoinitiators, and UVphotoinitiators (e.g., acetophenones (e.g., diethoxyacetophenone),phosphine oxides (e.g., diphenyl(2,4,6-trimethylbenzoyl) phosphineoxide, phenylbis(2,4,6-trimethylbenzoyl), phosphine oxide (PPO),Irgacure® 369,) and the like. Additional exemplary photoinitiators canbe found in U.S. Pat. No. 9,453,142, which is incorporated by referenceherein in its entirety.

In one embodiment, the resin can include a bioresorbable polyesteroligomer that can be present in an amount from about 5% to 90%, from 5%to 80%, from about 10% to 90%, or from about 10% to 80% by weight of theresin; a non-reactive diluent that can be present in an amount fromabout 1% to 70%, from about 1% to 50%, from about 5% to 70%, or fromabout 5% to 50% by weight of the resin; and a photoinitiator that can bepresent in an amount from about 0.1% to 4%, from about 0.1% to 2%, fromabout 0.2% to 4%, or from about 0.2% to 2% by weight of the resin.

In some embodiments, the resin can include a reactive diluent (includingdi- and tri-functional reactive diluents). For example, the reactivediluent can be present in an amount from about 1% to 50%, from about 1%to 40%, from about 5% to 50%, or from about 5% to 40% by weight of theresin. Non-limiting examples of reactive diluents include an acrylate, amethacrylate, a styrene, a vinyl amide, a vinyl ether, a vinyl ester,polymers containing any one or more of the foregoing, or any combinationthereof (e.g., acrylonitrile, styrene, divinyl benzene, vinyl toluene,methyl acrylate, ethyl acrylate, butyl acrylate, methyl (meth)acrylate,isobornyl acrylate (IBOA), isobornyl methacrylate (IBOMA), an alkylether of mono-, di- or triethylene glycol acrylate or methacrylate, afatty alcohol acrylate or methacrylate such as lauryl (meth)acrylate,and mixtures thereof).

In one embodiment, the resin can include a bioresorbable polyesteroligomer that can be present in an amount from about 5% to 90%, fromabout 5% to 80%, from about 10% to 90%, or from about 10% to 80% byweight of the resin; a non-reactive diluent that is present in an amountfrom about 1% to 70%, from about 1% to 50%, from about 5% to 70%, orfrom about 5% to 50% by weight of the resin; a photoinitiator that canbe present in an amount from about 0.1% to 4%, from about 0.1% to 2%,from about 0.2% to 4%, or from about 0.2% to 2% by weight of the resin;and a reactive diluent that can be present in an amount from about 1% to50%, from about 1% to 40%, from about 5% to 50%, or from about 5% to 40%by weight of the resin.

In some embodiments, the resin can include a filler. For example, thefiller can be present in an amount from about 1% to 50%, from about 1%to 40%, from about 2% to 50%, or from about 2% to 40% by weight of theresin. Any suitable filler may be used in connection with the presentinvention, including but not limited to bioresorbable polyesterparticles, sodium chloride particles, calcium triphosphate particles,sugar particles, and the like.

In one embodiment, the resin can include a bioresorbable polyesteroligomer that can be present in an amount from about 5% to 90%, fromabout 5% to 80%, from about 10% to 90%, or from about 10% to 80% byweight of the resin; a non-reactive diluent that is present in an amountfrom about 1% to 70%, from about 1% to 50%, from about 5% to 70%, orfrom about 5% to 50% by weight of the resin; a photoinitiator that canbe present in an amount from about 0.1% to 4%, from about 0.1% to 2%,from about 0.2% to 4%, or from about 0.2% to 2% by weight of the resin;a reactive diluent that can be present in an amount from about 1% to50%, from about 1% to 40%, from about 5% to 50%, or from about 5% to 40%by weight of the resin; and a filler that can be present in an amountfrom about 1% to 50%, from about 1% to 40%, from about 2% to 50%, orfrom about 2% to 40% by weight of the resin.

Further, depending upon the particular use of the adjunct, in someembodiments, the resin can have additional constituents. For example, incertain embodiments, the resin can include one or more additionalconstituents that can be present in an amount from about 0.1% to 10% byweight of the resin, from about 0.1% to 10% by weight of the resin, fromabout 1% to 20% by weight of the resin, or from about 1% to 10% byweight of the resin. Non-limiting examples of suitable additionalconstituents include pigments, dyes, diluents, active compounds orpharmaceutical compounds, detectable compounds (e.g., fluorescent,phosphorescent, radioactive), proteins, peptides, nucleic acids (DNA,RNA) such as siRNA, sugars, etc., including any combination thereof.

In some embodiments, the resin can include a non-reactive pigment or dyethat absorbs light, particularly UV light. Non-limiting examples ofsuitable non-reactive pigments or dyes include: (i) titanium dioxide(e.g., present in an amount from about 0.05% to 5%, from about 0.05% to1%, from about 0.1% to 1%, or from about 0.1% to 5% by weight of theresin), (ii) carbon black (e.g., present in an amount from about 0.05%to 5%, from about 0.05% to 1%, from about 0.1% to 1%, or from about 0.1%to 5% by weight of the resin), and/or (iii) an organic ultraviolet lightabsorber such as a hydroxybenzophenone, hydroxyphenylbenzotriazole,oxanilide, benzophenone, thioxanthone, hydroxyphenyltriazine, and/orbenzotriazole ultraviolet light absorber (e.g., Mayzo BLS1326) (e.g.,present in an amount from about 0.001% to 1%, 0.001% to 2%, from about0.001% to 4%, from about 0.005% to 1%, from about 0.005% to 2%, or fromabout 0.005% to 4% by weight of the resin). Additional exemplarynon-reactive pigments or dyes are disclosed in U.S. Pat. Nos. 3,213,058,6,916,867, 7,157,586, and 7,695,643, each of which is incorporated byreference herein in its entirety.

In some embodiments, a resin can include: (a) a (meth)acrylateterminated bioresorbable polyester oligomer present in an amount fromabout 5% to 80%, from about 5% to 90%, from about 10% to 80%, or fromabout 10% to 90% by weight of the resin; (b) a non-reactive diluentpresent in an amount from about 1% to 50%, from about 1% to 70%, fromabout 5% to 50%, or from about 5% to 70% by weight of the resin; and (c)a photoinitiator present in an amount from about 0.1% to 2%, from about0.1% to 4%, from about 0.2% to 2%, or from about 0.2% to 4 by weight ofthe resin. In such embodiments, the resin can also include (d) areactive diluent present in an amount from about 1% to 40%, from about1% to 50%, from about 5% to 40%, or from about 5% to 50% by weight ofthe resin, (e) a filler present in an amount from about 1% to 40%, fromabout 1% to 50%, from about 2% to 40%, or from about 2% to 50% by weightof the resin; (f) additional ingredient(s) (e.g., an active agent,detectable group, pigment or dye, and the like) present in an amountfrom about 0.1% to 10%, from about 0.1% to 20%, from about 1% to 10%, orfrom about 1% to 20% by weight of the resin; and/or (g) an additionalcross-linking agent (e.g., trimethylolpropane trimethacrylate (TMPTMA))present in an amount from about 1% to 5%, from about 1% to 10%, fromabout 2% to 5%, or from about 2% to 10% by weight of the resin.

In some embodiments, a resin can include:

(a) a (meth)acrylate terminated, linear or branched, bioresorbablepolyester oligomer of monomers in an ABA block, a BAB block, CBC block,or a BCB block, the oligomer being present in an amount from about 5% to80%, from about 5% to 90%, from about 10% to 80%, or from about 10% to90% by weight of the resin, wherein: A is poly(lactide) (PLA),poly(glycolide) (PGA), poly(lactide-co-glycolide) (PLGA), or anycombination thereof, with the PLGA containing lactide and glycolide in amolar ratio of either 90:10 to 60:40 lactide:glycolide or 40:60 to 10:90lactide:glycolide, and A has a molecular weight (Mn) from about 1kilodaltons to 4 kilodaltons, from about 1 kilodaltons to 10kilodaltons, from about 2 kilodaltons to 4 kilodaltons, or from about 2kilodaltons to 10 kilodaltons; B is polycaprolactone (PCL, PTMC, andPCLLA), poly(lactide-co-caprolactone) (PLACL),poly(glycolide-co-caprolactone) (PGACL) or poly(trimethylene carbonate)(PTMC) and has a molecular weight (Mn) from about 1 kilodaltons to 4kilodaltons, from about 1 kilodaltons to 10 kilodaltons, from about 1.6kilodaltons to 4 kilodaltons, or from about 1.6 kilodaltons to 10kilodaltons; and C is polydioxanone (PDO) and has a molecular weight(Mn) from about 1 kilodaltons to 4 kilodaltons, from about 1 kilodaltonsto 10 kilodaltons, from about 2 kilodaltons to 4 kilodaltons, or fromabout 2 kilodaltons to 10 kilodaltons;

(b) propylene carbonate present in an amount from about 1% to 50%, fromabout 1% to 70%, from about 5% to 50%, or from about 5% to 70% by weightof the resin;

(c) a photoinitiator present in the amount from about 0.1% to 2%, fromabout 0.1% to 4%, from about 0.2% to 2%, or from about 0.2% to 4% byweight of the resin;

(d) optionally, a reactive diluent present in the amount from about 1%to 40%, from about 1% to 50%, from about 5% to 40%, or from about 5% to50% by weight of the resin; and

(e) optionally, a filler present in the amount from about 1% to 40%,from about 1% to 50%, from about 2% to 40%, or from about 2% to 50% byweight of the resin.

Methods of Manufacturing

The non-fibrous adjuncts described herein can be formed from a matrixthat includes at least one fused bioabsorbable polymer, and thus it canbe formed using any additive manufacturing process. In some embodiments,the additive manufacturing process can be a continuous liquid interfaceproduction (CLIP) which involves curing liquid plastic resin usingultraviolet light. Details of the CLIP process are disclosed, forexample, in U.S. Pat. Nos. 9,211,678, 9,205,601, and 9,216,546; U.S.Patent Publication Nos. 2017/0129169, 2016/0288376, 2015/0360419,2015/0331402, 2017/0129167, 2018/0243976, 2018/0126630, and2018/0290374; J. Tumbleston et al., Continuous liquid interfaceproduction of 3D Objects, Science 347, 1349-1352 (2015); and R.Janusziewcz et al., Layerless fabrication with continuous liquidinterface production, Proc. Natl. Acad. Sci. USA 113, 11703-11708(2016); each of which is incorporated by reference herein in itsentirety. Non-limiting examples of other additive manufacturingapparatuses and methods that can be used to form the non-fibrousadjuncts described herein, and thus a matrix that includes at least onefused bioabsorbable polymer, can include bottom-up and top-down additivemanufacturing methods such as those described, for example, in U.S. Pat.Nos. 5,236,637, 5,391,072 5,529,473, 7,438,846, 7,892,474, and 8,110,135and U.S. Patent Publication Nos. 2013/0292862 and 2013/0295212, each ofwhich is incorporated by reference herein in its entirety, as well asfused deposition modeling (e.g., heating a thermoplastic filament andextruding the melted filament layer by layer), material jetting,2-photon polymerization, and holographic multi-focus polymerization asunderstood by a person skilled in the art.

In certain embodiments, after the additive manufacturing process, one ormore post-processing steps can be performed. For example, in someembodiments, the one or more post-processing steps can include washingthe adjunct (e.g., in an organic solvent such as acetone, isopropanol, aglycol ether such as dipropylene glycol methyl ether or DPM), wiping theadjunct (e.g., with an absorbent material, blowing with a compressed gasor air blade, etc.), centrifugal separation of residual resin,extraction of residual solvents, additional curing such as by floodexposure with ultraviolet light or the like so as to, for example,further react unpolymerized constituents of the adjunct, drying theadjunct (e.g., under a vacuum) to remove extraction solvents therefrom,or any combination thereof, in accordance with known techniques. The oneor more post-processing steps can cause the adjunct to shrink, andtherefore, in some embodiments, the adjunct can be produced in anenlarged form to offset such shrinkage.

In other embodiments, the non-fibrous adjuncts can be partially orwholly formed using any suitable non-additive manufacturing processes,such as injection molding, foaming, and forming processes as understoodby a person skilled in the art.

The stapling assemblies can be manufacturing in a variety of ways. Forexample, in some embodiments, as discussed above, the non-fibrousadjunct can be releasably attached to the staple cartridge by placing acartridge-contacting surface of the adjunct against a surface of thecartridge (e.g., an anvil-facing surface, e.g., a top or deck surface)so as to insert at least one attachment feature of the adjunct into atleast one surface feature (e.g., a recessed channel) of the cartridge(see e.g., FIGS. 19A-26C, 37A-39B, and 41A-41C;). Alternatively or inaddition, as discussed above, the non-fibrous adjunct can be configuredto receive one or more cartridge projections (e.g., staple pocketprojections) and/or staple legs (see e.g., FIGS. 45A-46B). Additionaldetails on the surface features and other exemplary surface features canbe found in U.S. Publication No. 2016/0106427, which is incorporated byreference herein in its entirety. Alternative or in addition, asdiscussed above, the non-fibrous adjunct can include an outer layer thatis in the form of an adhesive film that is used to releasably retain theadjunct to the staple cartridge (see e.g., FIG. 40 ). Additional detailson the adhesive film and other attachment methods can be found in U.S.Pat. No. 10,349,939, which is incorporated by reference herein in itsentirety.

The adjuncts and methods may be further understood with the followingnon-limiting examples.

EXAMPLES Examples 1-3: Preparation of a Difunctional Methacrylate (MA)Terminated Polyester Oligomer

Examples 1-3 describe the preparation of a difunctional, methacrylateterminated, polyester oligomer. The midblock is PLGA-PCL-PLGA, themolecular weight is 6 kilodaltons, and PCL is included as 40 wt. % ofthe total molecular weight (MW). PLGA is a random copolymer of lactide(L) and glycolide (G) with an L:G weight ratio of 1:1.

The molar ratios and masses of each reagent used for a 1 kg batch ofHO-PLGA-b-PCL-b-PLGA-OH synthesis as discussed in Examples 1 and 2 areprovided in Table 3 below.

TABLE 3 Molar ratios and mass of reagents for Examples 1 and 2 MolecularWeight Molar Density Mass Volume Reagent (g/mol) Ratio (g/mol) (g) (mL)Moles Caprolactone 114.14 22 1.03 400.0 388.4 3.50 (CL) Diethylene106.12  1 1.12  16.9  15.1 0.16 glycol (DEG) Stannous 405.12 2.38 × 1.25 0.15  0.12 3.81 × Octoate 10⁻³ 10⁻⁴ (Sn(Oct)) D,L-Lactide (L) 144.13 14— 321.4 — 2.22 Glycolide (G) 116.07 14 — 258.8 — 2.22

Example 1: HO-PCL-OH Synthesis

A round bottom flask was dried in a drying oven overnight and cooledunder N₂ flow to room temperature. Caprolactone and stannous octoatewere added to the round bottom flask via a glass syringe and syringeneedle. The reaction flask contents were heated to 130° C. Meanwhile,diethylene glycol was heated to 130° C. Once preheated, the diethyleneglycol was added to the reaction flask as an initiator and was allowedto react until complete monomer conversion. Monomer conversion wasmonitored using H¹ NMR. Once complete monomer conversion was reached,the reaction was stopped, and the reaction contents were allowed to coolto room temperature. The HO-PCL-OH was precipitated into cold MeOH fromchloroform to obtain a white solid. H¹ NMR, DSC, FTIR, and THF GPC wereused to characterize HO-PCL-OH.

Example 2: HO-PLGA-b-PCL-b-PLGA-OH Synthesis

HO-PCL-OH as prepared in Example 1 and varying amounts of D,L-lactideand glycolide were added into a round-bottom flask under N₂ and heatedto 140° C. to melt the reaction contents. After melting, the temperaturewas reduced to 120° C. and stannous octoate was added. The reactioncontinued with stirring while monitoring the monomer conversion with H¹NMR and THF GPC. Once the reaction reached the desired molecular weight,the reaction contents were cooled to room temperature, dissolved inchloroform, and precipitated into cold diethyl ether three times. Theprecipitate was dried under vacuum.

Example 3: MA-PLGA-b-PCL-b-PLGA-MA Synthesis

The molar ratios and masses of each reagent used to synthesize a 1 kgbatch of MA-PLGA-b-PCL-b-PLGA-MA are provided in Table 4 below.

TABLE 4 Molar ratios and mass of each reagent for Example 3 MolecularWeight Molar Density Mass Volume Reagent (g/mol) Ratio (g/mol) (g) (mL)Moles HO-PLGA- 6000 1   — 1000 — 0.17 b-PCL-b- PLGA-OH Meth-  104.54 3.81.07  66.2 61.9 0.63 acryloyl Chloride (MC) Triethyl-  101.19 3.8 0.72664.1 88.3 0.63 amine (TEA) Butylated  220.35 ~400 0.45 hydroxy- ppmtoluene (BHT) Dichloro- — 0.2 g/mL — — 5000 — methane (DCM)

HO-PLGA-b-PCL-b-PLGA-OH as prepared in Example 2 was dissolved inanhydrous DCM in a round bottom flask under N₂. Triethylamine and BHTwere added the reaction flask and the reaction flask was cooled to 0° C.in an ice water bath. The reaction flask was equipped with apressure-equalizing addition funnel that was charged with methacryloylchloride. Once the reaction flask reached 0° C., methacryloyl chloridewas added dropwise over 2 hours. The reaction proceeded for 12 hours at0° C. and then 24 hours at room temperature. Once complete, the reactioncontents were washed with distilled water 2 times to remove thetriethylamine hydrochloride salts, washed with saturated Na₂CO₃, andthen dried over magnesium sulfate. The collected and dried DCM layer wasdried with rotary evaporation. The final product was characterized withTHF GPC, H¹ NMR, FTIR, and DSC.

Examples 4-6: Preparation of a Tri-Arm MA Terminated Polyester Oligomer

Examples 4-6 describe the preparation of a tri-arm, or star shaped,bioresorbable polyester oligomer. Each arm is terminated withmethacrylate. Each arm has a molecular weight of 2 kilodaltons and is ablock copolymer of a random poly(lactide-co-glycolide) (PLGA) segmentand a poly(caprolactone) (PCL) segment with PCL being the core of theoligomer. The PCL is included as 40 wt % of the total molecular weight(MW). The PLGA is a random copolymer of lactide (L) and glycolide (G)with L:G weight ratio of 1:1.

Example 4: PCL-3OH Synthesis

The molar ratios and masses of each reagent used for a 1 kg batch of(PLGA-b-PCL)-3OH synthesis as discussed in Examples 4 and 5 are providedin Table 5 below.

TABLE 5 Example of molar ratios and mass of each reagent for Examples 4and 5 Molecular Weight Molar Density Mass Volume Reagent (g/mol) Ratio(g/mol) (g) (mL) Moles Caprolactone 114.14 22 1.03 400.0 388.4 3.50 (CL)Trimethylol- 134.07 1 1.08 21.4 19.8 0.16 propane (TMP) Stannous 405.122.38 × 1.25 0.15 0.12 3.81 × Octoate 10⁻³ 10⁻⁴ (Sn(Oct)) D,L-Lactide (L)144.13 14 — 321.4 — 2.22 Glycolide (G) 116.07 14 — 258.8 — 2.22

A round bottom flask was dried in a drying oven overnight and cooledunder N₂ flow to room temperature. Caprolactone and stannous octoatewere added to the round bottom flask via a glass syringe and syringeneedle. The reaction flask contents were heated to 130° C. Meanwhile,trimethylolpropane (TMP) was heated to 130° C. Once preheated, TMP wasadded to the reaction flask as an initiator and was allowed to reactuntil complete monomer conversion. Monomer conversion was monitoredusing H¹ NMR. Once complete monomer conversion was reached, the reactionwas stopped, and the reaction contents were allowed to cool to roomtemperature. The (PCL)-3OH was precipitated into cold MeOH fromchloroform to obtain a white solid. H1 NMR, DSC, FTIR, and GPC were usedto characterize (PCL)-3OH.

Example 5: (PCL-b-PLGA)-3OH Synthesis

(PCL)-3OH as prepared in Example 4 and varying amounts of D,L-lactideand glycolide were added into a round-bottom flask under N₂ and heatedto 140° C. to melt the reaction contents. After melting, the temperaturewas reduced to 120° C. and stannous octoate was added. The reactioncontinued with stirring while monitoring the monomer conversion with H¹NMR and THF GPC. Once the reaction reached the desired molecular weight,the reaction contents were cooled to room temperature, dissolved inchloroform and precipitated into cold diethyl ether three times. Theprecipitate was dried under vacuum.

Example 6: (PCL-b-PLGA)-3MA Synthesis

The molar ratio and masses of each reagent used to synthesize a 1 kgbatch of (PLGA-b-PCL)-3MA are provided in Table 6 below.

TABLE 6 Molar ratios and mass of each reagent for Example 6 MolecularWeight Molar Density Mass Volume Reagent (g/mol) Ratio (g/mol) (g) (mL)Moles (PLGA-b- 6000 1   — 1000 — 0.17 PCL)-3OH Methacryloyl 104.54 4.81.07  83.6 78.2 0.80 Chloride (MC) Triethylamine 101.19 4.8 0.726 80.9111.5 0.63 (TEA) Butylated 220.35 ~400 0.47 hydroxy- ppm toluene (BHT)Dichloro- — 0.2 — — 5000 — methane g/mL (DCM)

(PCL-b-PLGA)-3OH as prepared in Example 5 was dissolved in anhydrous DCMin a round bottom flask under N₂. Triethylamine (TEA) and BHT were addedthe reaction flask and the reaction flask was cooled to 0° C. in an icewater bath. The reaction flask was equipped with a pressure-equalizingaddition funnel that was charged with methacryloyl chloride. Once thereaction flask reached 0° C., methacryloyl chloride was added dropwiseover 2 hours. The reaction proceeded for 12 hours at 0° C. and then 24hours at room temperature. Once complete, the precipitate was removedvia vacuum filtration. The filtrate was collected and DCM was removedwith rotary evaporation. The resulting viscous oil was dissolved in THFand precipitated into cold methanol. The precipitate was dissolved inDCM and washed with aqueous HCl (3%, 2 times), saturated aqueous sodiumbicarbonate solution, and saturated aqueous sodium chloride, then driedover magnesium sulfate. The magnesium sulfate was filtered off viavacuum filtration, and the filtrate was collected. DCM was removed viarotary evaporation and the solid product was collected and characterizedwith GPC, H¹ NMR, FTIR, and DSC.

Example 7: Difunctional Oligomer Resin Formulation

The following constituents were mixed together in the following weightpercent (% by weight of the resin) to provide an exemplary resin foradditive manufacturing:

-   -   (1) 66.2% of the difunctional oligomer as prepared in Examples        1-3 above;    -   (2) 3.5% trimethylolpropane triacrylate (TMPTMA) reactive        diluent;    -   (3) 28.4% of N-methyl pyrrolidone (NMP) non-reactive diluent;        and    -   (4) 1.89% of Irgacure® 819 photoinitiator.

Example 8: Tri-Arm Oligomer Resin Formulation

The following constituents were mixed together in the following weightpercents (% by weight of the resin) to provide an exemplary resin foradditive manufacturing:

-   -   (1) 68.6% of the tri-arm oligomer as prepared in Examples 4-6        above;    -   (2) 29.4% of N-methyl pyrrolidone (NMP) non-reactive diluent;        and    -   (3) 1.96% of Irgacure® 819 photoinitiator.

Example 9: Additive Manufacturing and Post-Processing

Five exemplary adjuncts were prepared. The first exemplary adjunct(Adjunct 1) was structurally similar to adjunct 800 in FIGS. 8A-8F,except that the first adjunct was formed of two longitudinal rows of 20unit cells. The four other exemplary adjuncts were structural similar toadjuncts 3100, 3200, 3300, 3400 as illustrated in FIGS. 31A-31D (Adjunct2), FIGS. 32A-32D (Adjunct 3), FIGS. 33A-33E (Adjunct 4), and FIGS.34A-34E (Adjunct 5), respectively. The five adjuncts were prepared byadditive manufacturing that was carried out on a Carbon Inc. M1 or M2apparatus, available from Carbon Inc., 1089 Mills Way, Redwood CityCalif., 94063 in accordance with standard techniques. The resinformulation for each adjunct is provided in Table 7 below.

TABLE 7 Exemplary Adjunct Resin Formulations Adjunct Material ATPEComposition 1 ATPE-5 + MA-PLGA-PCL-PLGA-MA, 30% NMP + 40% PCL, 60% PLGA,5% TMPTMA 50:50 L:G, 5650 Da 2 ATPE-5 + MA-PLGA-PCL-PLGA-MA, (FIGS.31A-31D) 30% NMP 40% PCL, 60% PLGA, 50:50 L:G, 5650 Da 3 SIL30 (FIGS.32A-32D) 4 ATPE-5 + MA-PLGA-PCL-PLGA-MA, (FIGS. 33A-33E) 30% NMP 40%PCL, 60% PLGA, 50:50 L:G, 5650 Da 5 ATPE-5 + MA-PLGA-PCL-PLGA-MA, (FIGS.34A-34E) 30% NMP 40% PCL, 60% PLGA, 50:50 L:G, 5650 Da

When the resin contains a non-reactive diluent, the objects canexperience a global shrinkage upon washing/extraction by the extent ofthe non-reactive diluent loading amount. Therefore, a dimensionalscaling factor is applied to the part stereolithography (.stl) file or3D manufacturing format (3MF) file to enlarge the printed adjunct andintentionally account for subsequent shrinkage during post processingsteps.

Post processing of each adjunct was carried out as follows: afterremoving the build platform from the apparatus, excess resin is wipedfrom flat surfaces around the adjunct, and the platform left on its sideto drain for about 10 minutes. The adjunct was carefully removed fromthe platform. The adjunct was washed in acetone 3 times, for 30 secondseach on an orbital shaker at 280 rpm, followed by 5 minutes of dryingbetween washes. After the third wash, the adjunct was allowed to dry for30 minutes, and then flood cured for 20 seconds per side, in aPrimeCure™ ultraviolet flood curing apparatus.

Next, residual non-reactive diluent (e.g., N-methyl pyrrolidone orpropylene carbonate) was extracted from the adjunct by immersing theadjunct in acetone and shaking at room temperature on an orbital shakerfor ˜18 hours, with one solvent exchange after 12 hours. The adjunct wasthen removed from the acetone and vacuum dried overnight at 60° C. Theadjunct was then checked for residual solvent using extractions for GCMSand FTIR. If no residual was detected the part was checked fortackiness. If the adjunct remained tacky, it was then flood cured undernitrogen in an LED based flood lamp (such as a PCU LED N₂ flood lamp,available from Dreve Group, Unna, Germany).

Example 10: Stress-Strain Analysis of Representative Samples

The stress-strain curve for Adjunct 1 of Example 9 is illustrated inFIG. 56 , and the stress-strain curves for Adjuncts 2-5 of Example 9 areillustrated in FIG. 57 .

The stress-strain curves illustrated in FIGS. 56 and 57 were generatedby placing the adjuncts between a pair of 25 millimeter diametercircular stainless steel compression plates on an RSA-G2 solids analyzer(available from TA Instruments, 159 Lukens Drive, New Castle, Del. 19720USA), lowering the compression plate at 0.1 mm per step until theinitial axial force hits between 0.03-0.05 N, equilibrating at atemperature of 37° C. for 120 seconds, and carrying out the compressiontest (lowering the compression plate at 10 mm/min for 14 seconds untilreaching a gap height of 0.7 mm or an overload force of −17N, whicheveroccurs first, while recording real-time compression stress) to generatea stress-strain curve for each adjunct. As such, the stress-straincurves were generated by compressing each adjunct from its respectiveuncompressed height of 3 mm (within manufacturing tolerances) to itsrespective compressed height. The compressed height and strain for eachadjunct under while the adjunct was under an applied stress is providedin Table 8 below. These measurements are based on the actualmanufactured adjunct (including any measurement errors of themeasurement system, e.g., a bias of 50 μm to the uncompressed height,and/or manufacturing tolerances, e.g., a bias of 100 μm to theuncompressed height).

TABLE 8 Compressed Height and Strain Measurements for Adjuncts 1-5Compressed Measurement Condition Height (mm) Strain Adjunct 1 Appliedstress of 90 kPa 0.81 73 Adjunct 2 Applied stress of 30 kPa 1.53 49Adjunct 3 Applied stress of 9.43 kPa 1.2  60 Adjunct 4 Applied stress of30 kPa 1.5  50 Adjunct 5 Applied stress of 30 kPa 1.35 55

As shown in FIG. 56 , the adjunct formed of strut-less based unit cells,e.g., adjunct 800 in FIGS. 8A-8F, demonstrated: (i) A unit structurethat is sufficiently stable so that, even though the wall thicknessesare approximately 0.2 millimeters, the structures can be successfullyprinted and post-processed as described above; (ii) the adjunct goesthrough a broad range of buckling deformation and achieves a stressplateau between about 0.1 strain (about 10% deformation) to about 0.73strain (73% deformation); and (iii) the adjunct has a bi-stable nature,so the unit structure can be deformed and achieve a new stable form thatdoes not change until additional force is applied, potentially providingthe surgeon with tactile feedback of the deformation status of theadjunct.

As shown in FIG. 57 , the adjuncts formed of strut-based strut unitcells, e.g., adjunct 3100 in FIGS. 31A-31D, adjunct 3200 in FIGS.32A-32D, adjunct 3300 in FIGS. 33A-33E, and adjunct FIGS. 34A-34E,exhibited a stress “plateau” within 5 kPa to 20 kPa of stress over 10 to60 percent of strain. This result is based, at least in part, on thestructural configuration of the unit cells. In particular, each unitcell is designed such that the spacer struts (e.g., the struts of theinternal structure) fold inward without contacting one another duringcompression of the adjunct. As a result, densification of the adjunct(e.g., reaching solid height) can be delayed (e.g., occurs at a higherstrain).

Example 11: Stress-Strain Analysis of Representative Samples

Six exemplary adjuncts, referred to herein as Sample 1, Sample, 2,Sample 3, Sample 4, Sample 5, and Sample 6, respectively, were preparedin a similar manner as set forth in Example 9, except that the resinformulation for each of Samples 1-6 was: Trifunctional oligomer(methacrylate end groups) with midblock of PCL and endblock of PLGA(85/15 L:G ratio); target molecular weight of 6,000 Daltons. Sample 1was formed from repeating interconnected Schwarz-P structure unit cells,and Samples 2-5 were formed from respective repeating interconnectedmodified Schwarz-P structures in which the top and/or bottom of theinitial Schwarz-P structure were cropped. Thus, the geometric propertiesof the repeating unit cells of each Sample were different. A list ofgeometric unit cell properties for each adjunct is provided in Table 9below, which are based on theoretical/intended sizes.

TABLE 9 Exemplary Unit Cell Geometric Properties Lower Upper SampleGeometry Property Limit Limit 1 2 3 4 5 6 Unit Cell Height (mm)* 2 43.82 2.85 2.85 2.85 2.85 2.99 Unit Cell Width (mm)* 2 4 2.38 2.49 2.382.38 2.38 2.49 Unit Cell Length (mm)* 2 4 3.82 2.49 3.82 2.38 2.38 3.98Crop Distance from 0 1.5 0.00 0.00 0.00 0.00 0.42 0.20 Top (mm) CropDistance from 0 1.5 1.49 0.81 0.52 0.00 0.42 0.55 Bottom (mm) WallThickness (mm) 100 600 157.7 166 249 166 182.6 315.4 Overall Height(mm)** 1.8 3.5 2.32 2.04 2.32 2.85 1.99 2.24 *Using unit cell 810 inFIGS. 9A-9B as a reference, height extends in the x-direction, widthextends in the y-direction, and length extends in the z-direction.**Overall height reflects the uncompressed unit cell height of Sample 1(no-cropping) and the uncompressed, but cropped height of Samples 2-6.

The stress-strain curves of Samples 1-6 were generated in a similarmanner as set forth in Example 10, and are illustrated in FIG. 58 . Asshown, while each unit cell was formed of the same resin, each Samplehad a different stress-strain curve. As such, these differentstress-strain curves illustrate the relationship between the geometricproperties of the unit cells (e.g., height, width, length, and wallthickness) and the stress-strain response of the resulting adjunct whenbeing compressed from respective uncompressed heights (listed as overallheight in Table 9 above) to a respective compressed height. Thus, inaddition to the composition makeup of a unit cell, the various geometricproperties thereof also need to be taken into account, and thustailored, to effect an adjunct with a desired stress-strain response,such as the stress-strain responses described herein. The compressedheight and strain for each sample while the sample was under an appliedstress of 90 kPa is provided in Table 10 below. These measurements arebased on the actual manufactured adjunct (including any measurementerrors of the measurement system, e.g., a bias of 50 μm to theuncompressed height, and/or manufacturing tolerances, e.g., a bias of100 μm to the uncompressed height).

TABLE 10 Compressed Height and Strain Measurements for Samples 1-6 at 90kPa Sample Measurement at 90 kPa 1 2 3 4 5 6 Compressed Height (mm) 0.770.61 0.83 1.82 0.82 1.74 Strain 0.65 0.69 0.61 0.34 0.56 0.17

Examples 12-14: Preparation of a Tri-Arm MA Terminated PolyesterOligomer

Examples 12-14 describe the preparation of a tri-arm, or star shaped,bioresorbable polyester oligomer. Each arm is terminated withmethacrylate. Each arm has a molecular weight of 2 kilodaltons and is ablock copolymer of poly(L-lactic acid) (PLLA) andpoly(caprolactone-r-L-lactic acid) (PCLLA) with PCLLA being the core ofthe oligomer. The PCLLA is included as 70 wt. % of the total molecularweight (MW) and the CL:L ratio is 60:40.

The molar ratios and masses of each reagent used for a 1 kg batch of(PLLA-b-PCLLA)-3OH synthesis as discussed in Examples 12 and 13 areprovided in Table 11 below.

TABLE 11 Example of molar ratios and mass of each reagent for Examples12 and 13 Molecular Weight Molar Density Mass Volume Reagent (g/mol)Ratio (g/mol) (g) (mL) Moles Caprolactone 114.14 22 1.03 418 405 3.66(CL) Trimethylol- 134.07 1 1.08 21.4 19.8 0.16 propane (TMP) Stannous405.12 2.38 × 1.25 0.15 0.12 3.81 × Octoate 10⁻³ 10⁻⁴ (Sn(Oct))L-Lactide (L) 144.13 24 — 576 — 3.99

Example 12: PCLLA-3OH Synthesis

A round bottom flask was dried in a drying oven overnight and cooledunder N₂ flow to room temperature. Caprolactone, L-lactide and stannousoctoate were added to the round bottom flask. The reaction flaskcontents were heated to 130° C. Meanwhile, trimethylolpropane (TMP) washeated to 130° C. Once preheated, TMP was added to the reaction flask asan initiator and was allowed to react until complete monomer conversion.Monomer conversion was monitored using H¹ NMR. Once complete monomerconversion was reached, the reaction was stopped, and the reactioncontents were allowed to cool to room temperature. The (PCLLA)-3OH wasprecipitated into cold MeOH from chloroform to obtain a white solid. H¹NMR, DSC, FTIR, and THF GPC were used to characterize (PCLLA)-3OH.

Example 13: (PLLA-b-PCLLA)-3OH Synthesis

(PCLLA)-3OH as prepared in Example 12 and L-lactide were added into around-bottom flask under N₂ and heated to 140° C. to melt the reactioncontents. After melting, the temperature was reduced to 120° C. andstannous octoate was added. The reaction continued with stirring whilemonitoring the monomer conversion with H¹ NMR and THF GPC. Once thereaction reached the desired molecular weight, the reaction contentswere cooled to room temperature, dissolved in chloroform andprecipitated into cold diethyl ether three times. The precipitate wasdried under vacuum.

Example 14: (PLLA-b-PCLLA)-3MA Synthesis

The molar ratios and masses of each reagent used to synthesize a 1 kgbatch of (PLLA-b-PCLLA)-3MA are provided in Table 12 below.

TABLE 12 Molar ratios and mass of each reagent for Example 14. MolecularWeight Molar Density Mass Volume Reagent (g/mol) Ratio (g/mol) (g) (mL)Moles (PLLA-b- 6000 1   — 1000 — 0.17 PCLLA)- 3OH Methacrylol  104.544.8 1.07   83.6  78.2 0.80 Chloride (MC) Triethyl-  101.19 4.8 0.726 80.9  111.5 0.63 amine (TEA) Butylated  220.35 ~400   0.47 hydroxy- ppmtoluene (BHT) Dichloro- — 0.2 — — 5000 — methane g/mL (DCM)

(PLLA-b-PCLLA)-3OH as prepared in Example 13 was dissolved in anhydrousDCM in a round bottom flask under N₂. Triethylamine (TEA) and a 400 ppmBHT were added the reaction flask and the reaction flask was cooled to0° C. in an ice water bath. The reaction flask was equipped with apressure-equalizing addition funnel that was charged with methacrylolchloride. Once the reaction flask reached 0° C., methacrylol chloridewas added dropwise over 2 hours. The reaction proceeded for 12 hours at0° C. and then 24 hours at room temperature. Once complete, theprecipitate was removed via vacuum filtration. The filtrate wascollected and DCM was removed with rotary evaporation. The resultingviscous oil was dissolved in THF and precipitated into cold methanol.The precipitate was dissolved in DCM and washed with aqueous HCL (3%, 2times), saturated aqueous sodium bicarbonate solution, and saturatedaqueous sodium chloride, and then dried over magnesium sulfate. Themagnesium sulfate was filtered off via vacuum filtration, and thefiltrate was collected. DCM was removed via rotary evaporation and thesolid product was collected and characterized with THF GPC, H¹ NMR,FTIR, and DSC.

Example 15: Difunctional Oligomer Resin Formulation

The following constituents were mixed together in the following weightpercent (% by weight of the resin) to provide an exemplary lightpolymerizable resin for additive manufacturing:

-   -   (1) 58.82% of the difunctional oligomer prepared in Examples        12-13 above;    -   (2) 39.22% propylene carbonate (PC) non-reactive diluent; and    -   (3) 1.96% of Irgacure® 819 photoinitiator.

The instruments disclosed herein can be designed to be disposed of aftera single use, or they can be designed to be used multiple times. Ineither case, however, the instrument can be reconditioned for reuseafter at least one use. Reconditioning can include any combination ofthe steps of disassembly of the instrument, followed by cleaning orreplacement of particular pieces and subsequent reassembly. Inparticular, the instrument can be disassembled, and any number of theparticular pieces or parts of the instrument can be selectively replacedor removed in any combination. Upon cleaning and/or replacement ofparticular parts, the instrument can be reassembled for subsequent useeither at a reconditioning facility, or by a surgical team immediatelyprior to a surgical procedure. Those skilled in the art will appreciatethat reconditioning of an instrument can utilize a variety of techniquesfor disassembly, cleaning/replacement, and reassembly. Use of suchtechniques, and the resulting reconditioned instrument, are all withinthe scope of the present application.

Further, in the present disclosure, like-named components of theembodiments generally have similar features, and thus within aparticular embodiment each feature of each like-named component is notnecessarily fully elaborated upon. Additionally, to the extent thatlinear or circular dimensions are used in the description of thedisclosed systems, devices, and methods, such dimensions are notintended to limit the types of shapes that can be used in conjunctionwith such systems, devices, and methods. A person skilled in the artwill recognize that an equivalent to such linear and circular dimensionscan easily be determined for any geometric shape. Sizes and shapes ofthe systems and devices, and the components thereof, can depend at leaston the anatomy of the subject in which the systems and devices will beused, the size and shape of components with which the systems anddevices will be used, and the methods and procedures in which thesystems and devices will be used.

It will be appreciated that the terms “proximal” and “distal” are usedherein with reference to a user, such as a clinician, gripping a handleof an instrument. Other spatial terms such as “front” and “rear”similarly correspond respectively to distal and proximal. It will befurther appreciated that for convenience and clarity, spatial terms suchas “vertical” and “horizontal” are used herein with respect to thedrawings. However, surgical instruments are used in many orientationsand positions, and these spatial terms are not intended to be limitingand absolute.

Values or ranges may be expressed herein as “about” and/or from/of“about” one particular value to another particular value. When suchvalues or ranges are expressed, other embodiments disclosed include thespecific value recited and/or from/of the one particular value toanother particular value. Similarly, when values are expressed asapproximations, by the use of antecedent “about,” it will be understoodthat here are a number of values disclosed therein, and that theparticular value forms another embodiment. It will be further understoodthat there are a number of values disclosed therein, and that each valueis also herein disclosed as “about” that particular value in addition tothe value itself. In embodiments, “about” can be used to mean, forexample, within 10% of the recited value, within 5% of the recited valueor within 2% of the recited value.

For purposes of describing and defining the present teachings, it isnoted that unless indicated otherwise, the term “substantially” isutilized herein to represent the inherent degree of uncertainty that maybe attributed to any quantitative comparison, value, measurement, orother representation. The term “substantially” is also utilized hereinto represent the degree by which a quantitative representation may varyfrom a stated reference without resulting in a change in the basicfunction of the subject matter at issue.

One skilled in the art will appreciate further features and advantagesof the invention based on the above-described embodiments. Accordingly,the invention is not to be limited by what has been particularly shownand described, except as indicated by the appended claims. Allpublications and references cited herein are expressly incorporatedherein by reference in their entirety. Any patent, publication, orinformation, in whole or in part, that is said to be incorporated byreference herein is only to the extent that the incorporated materialdoes not conflict with existing definitions, statements, or otherdisclosure material set forth in this document. As such the disclosureas explicitly set forth herein supersedes any conflicting materialincorporated herein by reference.

What is claimed is:
 1. A stapling assembly for use with a surgicalstapler, comprising: a cartridge extending from a first lateral end to asecond lateral end with a longitudinal axis extending therebetween, thecartridge having a plurality of staples disposed therein, each staplehaving staple legs, the plurality of staples are arranged intolongitudinal rows that extend between the first and second lateral ends,each longitudinal row having a frequency of staples in which the staplesare arranged along the longitudinal axis and configured to be deployedinto tissue; and a non-fibrous adjunct formed of at least one fusedbioabsorbable polymer and configured to be releasably retained on thecartridge such that the adjunct can be attached to tissue by the staplesin the cartridge, the adjunct comprises a lattice structure having aplurality of repeating unit cells, each unit cell having a non-uniformthickness and a surface contour that is defined by triply periodicminimal surfaces, the plurality of repeating unit cells being arrangedinto longitudinal rows in which each longitudinal row has a frequency ofunit cells; wherein the frequency of unit cells is different than thefrequency of staples and the staples legs of the plurality of staplesare configured to advance through different portions of the plurality ofrepeating unit cells, wherein the different portions have differentthickness relative to each other.
 2. The stapling assembly of claim 1,wherein the frequency of staples is greater than the frequency of unitcells in each corresponding longitudinal row.
 3. The stapling assemblyof claim 1, wherein each staple of the plurality of staples includes afirst staple leg configured to advance through a first portion of theadjunct with a first thickness and a second staple leg configured toadvance through a second portion of the adjunct with a second thicknessthat is greater than the first thickness.
 4. The stapling assembly ofclaim 1, wherein each staple of the plurality of staples includes afirst staple leg configured to advance through a first portion of theadjunct with a first thickness and a second staple leg configured toadvance through a second portion of the adjunct with a second thicknessthat is less than the first thickness.
 5. The stapling assembly of claim1, wherein at least a portion of the staples of the plurality of staplesinclude uniform staples legs that are identical to each other.
 6. Thestapling assembly of claim 1, wherein at least a portion of the staplesof the plurality of staples include staple legs that differ from eachanother.
 7. The stapling assembly of claim 1, wherein the plurality ofrepeating unit cells are_Schwarz-P structures.
 8. The stapling assemblyof claim 1, wherein the adjunct while under an applied stress in a rangeof 30 kPa to 90 kPa, is configured to undergo a strain in a range of 0.1to 0.9.
 9. The stapling assembly of claim 8, wherein the strain is inthe range of 0.1 to 0.7.